AIO_FSYNC
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
aio_fsync
--- asynchronous file synchronization
SYNOPSIS
#include <aio.h>
int aio_fsync(int op, struct aiocb *aiocbp);
DESCRIPTION
The
aio_fsync()
function shall asynchronously perform a file synchronization operation,
as specified by the
op
argument, for I/O operations associated with the file indicated by the
file descriptor
aio_fildes
member of the
aiocb
structure referenced by the
aiocbp
argument and queued at the time of the call to
aio_fsync().
The function call shall return when the synchronization request has been
initiated or queued to the file or device (even when the data cannot be
synchronized immediately).
If
op
is O_DSYNC,
all currently queued I/O operations shall be completed as if by a call to
fdatasync();
that is, as defined for synchronized I/O data integrity completion.
If
op
is O_SYNC,
all currently queued I/O operations shall be completed as if by a call to
fsync();
that is, as defined for synchronized I/O file integrity completion.
If the
aio_fsync()
function fails, or if the operation queued by
aio_fsync()
fails, then outstanding I/O operations are not guaranteed to have been
completed.
If
aio_fsync()
succeeds, then it is only the I/O that was queued at the time of the
call to
aio_fsync()
that is guaranteed to be forced to the relevant completion state. The
completion of subsequent I/O on the file descriptor is not guaranteed
to be completed in a synchronized fashion.
The
aiocbp
argument refers to an asynchronous I/O control block. The
aiocbp
value may be used as an argument to
aio_error()
and
aio_return()
in order to determine the error status and return status, respectively,
of the asynchronous operation while it is proceeding. When the request
is queued, the error status for the operation is
[EINPROGRESS].
When all data has been successfully transferred, the error status shall
be reset to reflect the success or failure of the operation. If the
operation does not complete successfully, the error status for the
operation shall be set to indicate the error. The
aio_sigevent
member determines the asynchronous notification to occur as specified
in
Section 2.4.1, Signal Generation and Delivery
when all operations have achieved synchronized I/O completion. All
other members of the structure referenced by
aiocbp
are ignored. If the control block referenced by
aiocbp
becomes an illegal address prior to asynchronous I/O completion, then
the behavior is undefined.
If the
aio_fsync()
function fails or
aiocbp
indicates an error condition, data is not guaranteed to have been
successfully transferred.
RETURN VALUE
The
aio_fsync()
function shall return the value 0 if the I/O operation is successfully
queued; otherwise, the function shall return the value -1 and set
errno
to indicate the error.
ERRORS
The
aio_fsync()
function shall fail if:
- EAGAIN
-
The requested asynchronous operation was not queued due to
temporary resource limitations.
- EBADF
-
The
aio_fildes
member of the
aiocb
structure referenced by the
aiocbp
argument is not a valid file descriptor.
- EINVAL
-
This implementation does not support synchronized I/O for this file.
- EINVAL
-
The
aio_fildes
member of the
aiocb
structure refers to a file on which an
fsync()
operation is not possible.
- EINVAL
-
A value of
op
other than O_DSYNC or O_SYNC was specified, or O_DSYNC was specified and
the implementation does not provide runtime support for the Synchronized
Input and Output option, or O_SYNC was specified and the implementation
does not provide runtime support for the File Synchronization option.
In the event that any of the queued I/O operations fail,
aio_fsync()
shall return the error condition defined for
read()
and
write().
The error is returned in the error status for the asynchronous operation,
which can be retrieved using
aio_error().
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
Note that even if the file descriptor is not open for writing, if
there are any pending write requests on the underlying file, then
that I/O will be completed prior to the return of a call to
aio_error()
or
aio_return()
indicating that the operation has completed.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
aio_error(),
aio_return(),
fcntl(),
fdatasync(),
fsync(),
open(),
read(),
write()
The Base Definitions volume of POSIX.1-2017,
<aio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear
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https://www.kernel.org/doc/man-pages/reporting_bugs.html .