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 open for writing.

       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

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fcntl(), fdatasync(), fsync(), open(), read(), write()

       The Base Definitions volume of POSIX.1‐2008, <aio.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2013 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX),  The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/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 .