FreeBSD-5.3/lib/libc/sys/msync.2

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.\"	@(#)msync.2	8.2 (Berkeley) 6/21/94
.\" $FreeBSD: src/lib/libc/sys/msync.2,v 1.27 2004/06/30 20:09:10 ru Exp $
.\"
.Dd June 21, 1994
.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 EINVAL
The
.Fa len
argument
is too large or negative.
.It Bq Er EINVAL
The
.Fa flags
argument
was both MS_ASYNC and MS_INVALIDATE.
Only one of these flags is allowed.
.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 .