153 lines
4.2 KiB
Groff
153 lines
4.2 KiB
Groff
.\" $NetBSD: aio_fsync.3,v 1.5 2009/05/13 12:56:05 wiz Exp $
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.\"
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.\" Copyright (c) 2007 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd June 17, 2007
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.Dt AIO_FSYNC 3
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.Os
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.Sh NAME
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.Nm aio_fsync
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.Nd asynchronous data synchronization of file (REALTIME)
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.Sh LIBRARY
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.Lb librt
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.Sh SYNOPSIS
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.In aio.h
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.Ft int
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.Fn aio_fsync "int op" "struct aiocb *aiocbp"
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.Sh DESCRIPTION
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The
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.Fn aio_fsync
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system call allows the calling process to force all modified data
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associated with the file descriptor
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.Fa aiocbp-\*[Gt]aio_fildes
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to be flushed to the stable storage device.
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The call returns immediately after the synchronization request has been
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enqueued to the descriptor; the synchronization may or may not have
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completed at the time the call returns.
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If the request could not be enqueued, generally due to invalid arguments,
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the call returns without having enqueued the request.
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.Pp
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The
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.Fa op
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argument could be set only to
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.Dv O_DSYNC
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or
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.Dv O_SYNC .
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If
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.Fa op
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is
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.Dv O_DSYNC ,
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then
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.Fn aio_fsync
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does the same as a
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.Fn fdatasync
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call, if
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.Dv O_SYNC ,
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then the same as
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.Fn fsync .
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.Pp
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If
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.Dv _POSIX_PRIORITIZED_IO
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is defined, and the descriptor supports it, then the enqueued
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operation is submitted at a priority equal to that of the calling
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process minus
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.Fa aiocbp-\*[Gt]aio_reqprio .
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.Pp
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The
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.Fa aiocbp
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pointer may be subsequently used as an argument to
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.Fn aio_return
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and
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.Fn aio_error
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in order to determine return or error status for the enqueued operation
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while it is in progress.
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.Sh RESTRICTIONS
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The asynchronous I/O control buffer
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.Fa aiocbp
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should be zeroed before the
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.Fn aio_fsync
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system call to avoid passing bogus context information to the kernel.
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.Pp
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Modifications of the Asynchronous I/O Control Block structure after
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the request has been enqueued, but before the request has completed,
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are not allowed.
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.Sh RETURN VALUES
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.Rv -std aio_fsync
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.Sh ERRORS
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The
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.Fn aio_fsync
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system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.El
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.Pp
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The following conditions may be synchronously detected when the
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.Fn aio_fsync
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system call is made, or asynchronously, at any time thereafter.
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If they are detected at call time,
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.Fn aio_fsync
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returns \-1 and sets
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.Va errno
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appropriately; otherwise the
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.Fn aio_return
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system call must be called, and will return \-1, and
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.Fn aio_error
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must be called to determine the actual value that would have been
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returned in
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.Va errno .
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa aiocbp-\*[Gt]aio_fildes
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is invalid for writing.
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.It Bq Er EINVAL
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This implementation does not support synchronized I/O for this file,
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or the
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.Fa op
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argument is neither set to
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.Dv O_DSYNC
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nor
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.Dv O_SYNC .
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.El
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.Sh SEE ALSO
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.Xr fcntl 2 ,
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.Xr fdatasync 2 ,
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.Xr fsync 2 ,
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.Xr aio_error 3 ,
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.Xr aio_read 3 ,
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.Xr aio_write 3
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.Sh STANDARDS
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The
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.Fn aio_fsync
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system call is expected to conform to the
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.St -p1003.1-2001
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standard.
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.Sh HISTORY
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The
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.Fn aio_fsync
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system call first appeared in
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.Nx 5.0 .
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