Provided by:
libaio-dev_0.3.106-5ubuntu2_i386 
NAME
io_fsync - Synchronize a file’s complete in-core state with that on
disk
SYNOPSYS
#include <errno.h>
#include <libaio.h>
int io_fsync(io_context_t ctx, struct iocb *iocb, io_callback_t cb, int fd)
struct iocb {
void *data;
unsigned key;
short aio_lio_opcode;
short aio_reqprio;
int aio_fildes;
};
typedef void (*io_callback_t)(io_context_t ctx, struct iocb *iocb, long res, long res2);
DESCRIPTION
When dealing with asynchronous operations it is sometimes necessary to
get into a consistent state. This would mean for AIO that one wants to
know whether a certain request or a group of request were processed.
This could be done by waiting for the notification sent by the system
after the operation terminated, but this sometimes would mean wasting
resources (mainly computation time).
Calling this function forces all I/O operations operating queued at the
time of the function call operating on the file descriptor
iocb->io_fildes into the synchronized I/O completion state . The
io_fsync function returns immediately but the notification through the
method described in io_callback will happen only after all requests for
this file descriptor have terminated and the file is synchronized.
This also means that requests for this very same file descriptor which
are queued after the synchronization request are not affected.
Returns 0, otherwise returns errno.
ERRORS
EFAULT iocbs referenced data outside of the program’s accessible
address space.
EINVAL ctx refers to an unitialized aio context, the iocb pointed to by
iocbs contains an improperly initialized iocb,
EBADF The iocb contains a file descriptor that does not exist.
EINVAL The file specified in the iocb does not support the given io
operation.
io(3), io_cancel(3), io_getevents(3), io_prep_pread(3),
io_prep_pwrite(3), io_queue_init(3), io_queue_release(3),
io_queue_run(3), io_queue_wait(3), io_set_callback(3), io_submit(3),
errno(3)