freebsd-skq/lib/libc/sys/msync.2

.\" Copyright (c) 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
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.\" modification, are permitted provided that the following conditions
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.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\"	@(#)msync.2	8.2 (Berkeley) 6/21/94
.\" $FreeBSD$
.\"
.Dd March 18, 2012
.Dt MSYNC 2
.Os
.Sh NAME
.Nm msync
.Nd synchronize a mapped region
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/mman.h
.Ft int
.Fn msync "void *addr" "size_t len" "int flags"
.Sh DESCRIPTION
The
.Fn msync
system call
writes any modified pages back to the file system and updates
the file modification time.
If
.Fa len
is 0, all modified pages within the region containing
.Fa addr
will be flushed;
if
.Fa len
is non-zero, only those pages containing
.Fa addr
and
.Fa len-1
succeeding locations will be examined.
The
.Fa flags
argument may be specified as follows:
.Pp
.Bl -tag -width ".Dv MS_INVALIDATE" -compact
.It Dv MS_ASYNC
Return immediately
.It Dv MS_SYNC
Perform synchronous writes
.It Dv MS_INVALIDATE
Invalidate all cached data
.El
.Sh RETURN VALUES
.Rv -std msync
.Sh ERRORS
The
.Fn msync
system call
will fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
Some or all of the pages in the specified region are locked and
.Dv MS_INVALIDATE
is specified.
.It Bq Er EINVAL
The
.Fa addr
argument
is not a multiple of the hardware page size.
.It Bq Er ENOMEM
The addresses in the range starting at
.Fa addr
and continuing for
.Fa len
bytes are outside the range allowed for the address space of a
process or specify one or more pages that are not mapped.
.It Bq Er EINVAL
The
.Fa flags
argument
was both MS_ASYNC and MS_INVALIDATE.
Only one of these flags is allowed.
.It Bq Er EIO
An error occurred while writing at least one of the pages in
the specified region.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mincore 2 ,
.Xr mlock 2 ,
.Xr mprotect 2 ,
.Xr munmap 2
.Sh HISTORY
The
.Fn msync
system call first appeared in
.Bx 4.4 .
.Sh BUGS
The
.Fn msync
system call is usually not needed since
.Bx
implements a coherent file system buffer cache.
However, it may be used to associate dirty VM pages with file system
buffers and thus cause them to be flushed to physical media sooner
rather than later.
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" Copyright (c) 1991, 1993`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96 2017-02-28 23:42:47 +00:00			`.\" 3. Neither the name of the University nor the names of its contributors`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
			`.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
			`.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE`
			`.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
			`.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
			`.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
			`.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
			`.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
			`.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
			`.\" SUCH DAMAGE.`
			`.\"`
Merge from Lite2 onto mainline - - add undelete() and undelete.2 (requires libc minor bump some time) - man page updates 1997-03-11 11:35:56 +00:00			`.\" @(#)msync.2 8.2 (Berkeley) 6/21/94`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\"`
Do not claim that msync(2) is obsoleted [1]. Document EIO from msync(2). Inspired by PR: docs/165929 [1] Reviewed by: jilles MFC after: 2 weeks 2012-03-17 23:55:18 +00:00			`.Dd March 18, 2012`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Dt MSYNC 2`
			`.Os`
			`.Sh NAME`
			`.Nm msync`
			`.Nd synchronize a mapped region`
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following. 2000-04-21 09:42:15 +00:00			`.Sh LIBRARY`
			`.Lb libc`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In sys/mman.h`
Minor mdoc fixes in msync.2 and munmap.2. Add RETURN VALUES and ERRORS sections to mincore. Closes PR# 1493. 1997-01-11 23:33:18 +00:00			`.Ft int`
Convert caddr_t --> void * for sys/mman.h functions. mlock, mmap, mprotect, msync, munlock, and munmap are defined by POSIX as taking void . The const modifier has been added to mlock, munlock, and mprotect as the standard dictates. minherit comes from OpenBSD and has been updated to conform with their recent change to void . madvise and mincore are not defined by POSIX, but their arguments have been modified to be consistent with the POSIX-defined functions. mincore takes a const pointer, but madvise does not due to the MADV_FREE case. Discussed with: bde 1997-12-31 01:22:01 +00:00			`.Fn msync "void *addr" "size_t len" "int flags"`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh DESCRIPTION`
			`The`
			`.Fn msync`
			`system call`
Uniformly refer to a file system as "file system". Approved by: re 2002-12-12 17:26:04 +00:00			`writes any modified pages back to the file system and updates`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`the file modification time.`
			`If`
			`.Fa len`
			`is 0, all modified pages within the region containing`
			`.Fa addr`
			`will be flushed;`
			`if`
			`.Fa len`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`is non-zero, only those pages containing`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Fa addr`
			`and`
Correct wording on range of addresses examined by `msync(2)'. PR: 7180 1998-07-09 06:16:22 +00:00			`.Fa len-1`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`succeeding locations will be examined.`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`The`
			`.Fa flags`
			`argument may be specified as follows:`
Markup, grammar, and spelling fixes. 2004-06-30 20:09:10 +00:00			`.Pp`
			`.Bl -tag -width ".Dv MS_INVALIDATE" -compact`
			`.It Dv MS_ASYNC`
			`Return immediately`
			`.It Dv MS_SYNC`
			`Perform synchronous writes`
			`.It Dv MS_INVALIDATE`
			`Invalidate all cached data`
			`.El`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.Sh RETURN VALUES`
Use the ``.Rv -std'' mdoc(7) macro in appropriate cases. Reviewed by: ru 2001-08-09 13:32:13 +00:00			`.Rv -std msync`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.Sh ERRORS`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`The`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.Fn msync`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`will fail if:`
			`.Bl -tag -width Er`
- Add documentation for EBUSY. - Remove EIO. - Add a cross reference to mlock(2). 2003-11-14 07:18:12 +00:00			`.It Bq Er EBUSY`
			`Some or all of the pages in the specified region are locked and`
Markup, grammar, and spelling fixes. 2004-06-30 20:09:10 +00:00			`.Dv MS_INVALIDATE`
			`is specified.`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.It Bq Er EINVAL`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`The`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.Fa addr`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`argument`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`is not a multiple of the hardware page size.`
msync(2) must return ENOMEM and not EINVAL when the address is outside the allowed range or when one or more pages are not mapped. This according to The Open Group Base Specifications Issue 7. Discussed with: attilio, Bruce Evans Reviewed by: alc, Garrett Cooper Reported by: ATF MFC after: 2 weeks Sponsored by: EMC / Isilon storage division 2014-05-07 08:38:02 +00:00			`.It Bq Er ENOMEM`
			`The addresses in the range starting at`
			`.Fa addr`
			`and continuing for`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.Fa len`
msync(2) must return ENOMEM and not EINVAL when the address is outside the allowed range or when one or more pages are not mapped. This according to The Open Group Base Specifications Issue 7. Discussed with: attilio, Bruce Evans Reviewed by: alc, Garrett Cooper Reported by: ATF MFC after: 2 weeks Sponsored by: EMC / Isilon storage division 2014-05-07 08:38:02 +00:00			`bytes are outside the range allowed for the address space of a`
			`process or specify one or more pages that are not mapped.`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.It Bq Er EINVAL`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`The`
Updated manual page to indicate flags argument; added return value and errors section. 1995-03-25 17:24:47 +00:00			`.Fa flags`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`argument`
Remove single-space hard sentence breaks. These degrade the quality of the typeset output, tend to make diffs harder to read and provide bad examples for new-comers to mdoc. 2000-03-02 09:14:21 +00:00			`was both MS_ASYNC and MS_INVALIDATE.`
			`Only one of these flags is allowed.`
Do not claim that msync(2) is obsoleted [1]. Document EIO from msync(2). Inspired by PR: docs/165929 [1] Reviewed by: jilles MFC after: 2 weeks 2012-03-17 23:55:18 +00:00			`.It Bq Er EIO`
msync(2) must return ENOMEM and not EINVAL when the address is outside the allowed range or when one or more pages are not mapped. This according to The Open Group Base Specifications Issue 7. Discussed with: attilio, Bruce Evans Reviewed by: alc, Garrett Cooper Reported by: ATF MFC after: 2 weeks Sponsored by: EMC / Isilon storage division 2014-05-07 08:38:02 +00:00			`An error occurred while writing at least one of the pages in`
Do not claim that msync(2) is obsoleted [1]. Document EIO from msync(2). Inspired by PR: docs/165929 [1] Reviewed by: jilles MFC after: 2 weeks 2012-03-17 23:55:18 +00:00			`the specified region.`
Prepare for mdoc(7)NG. 2000-12-29 14:08:20 +00:00			`.El`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SEE ALSO`
			`.Xr madvise 2 ,`
Minor mdoc fixes in msync.2 and munmap.2. Add RETURN VALUES and ERRORS sections to mincore. Closes PR# 1493. 1997-01-11 23:33:18 +00:00			`.Xr mincore 2 ,`
- Add documentation for EBUSY. - Remove EIO. - Add a cross reference to mlock(2). 2003-11-14 07:18:12 +00:00			`.Xr mlock 2 ,`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Xr mprotect 2 ,`
Sort cross references. 1997-01-20 23:23:22 +00:00			`.Xr munmap 2`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh HISTORY`
			`The`
			`.Fn msync`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call first appeared in`
Correctly use .Fn instead of .Nm to reference function names in a bunch of man pages. Use the correct .Bx (BSD UNIX) or .At (AT&T UNIX) macros instead of explicitly specifying the version in the text in a bunch of man pages. 1996-08-22 23:31:07 +00:00			`.Bx 4.4 .`
Add a BUGS section and copy the wording from mmap(2)'s MAP_NOSYNC, documenting the obsoleteness of the msync(2) syscall and its single remaining purpose. PR: 70916 Submitted by: Radim Kolar <hsn@netmag.cz> MFC after: 3 days 2004-09-03 06:24:25 +00:00			`.Sh BUGS`
			`The`
			`.Fn msync`
Do not claim that msync(2) is obsoleted [1]. Document EIO from msync(2). Inspired by PR: docs/165929 [1] Reviewed by: jilles MFC after: 2 weeks 2012-03-17 23:55:18 +00:00			`system call is usually not needed since`
Add a BUGS section and copy the wording from mmap(2)'s MAP_NOSYNC, documenting the obsoleteness of the msync(2) syscall and its single remaining purpose. PR: 70916 Submitted by: Radim Kolar <hsn@netmag.cz> MFC after: 3 days 2004-09-03 06:24:25 +00:00			`.Bx`
			`implements a coherent file system buffer cache.`
			`However, it may be used to associate dirty VM pages with file system`
			`buffers and thus cause them to be flushed to physical media sooner`
			`rather than later.`