AIO_FSYNC(3)               POSIX Programmer's Manual              AIO_FSYNC(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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 in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                         AIO_FSYNC(3)
