June 17, 2007 AIO_FSYNC 3

### NAME

aio_fsync - asynchronous data synchronization of file (REALTIME)

### LIBRARY

POSIX Real-time Library (librt, -lrt)

### SYNOPSIS

```int` aio_fsync(```int op``, struct aiocb *aiocbp`)

### DESCRIPTION

The aio_fsync(``) system call allows the calling process to force all modified data associated with the file descriptor ```aiocbp->aio_fildes` to be flushed to the stable storage device. The call returns immediately after the synchronization request has been enqueued to the descriptor; the synchronization may or may not have completed at the time the call returns. If the request could not be enqueued, generally due to invalid arguments, the call returns without having enqueued the request.

The ```op` argument could be set only to ```O_DSYNC` or ```O_SYNC`. If ```op` is ```O_DSYNC`, then aio_fsync(``) does the same as a fdatasync(``) call, if ```O_SYNC`, then the same as fsync(``).

If ```_POSIX_PRIORITIZED_IO` is defined, and the descriptor supports it, then the enqueued operation is submitted at a priority equal to that of the calling process minus ```aiocbp->aio_reqprio`.

The ```aiocbp` pointer may be subsequently used as an argument to aio_return(``) and aio_error(``) in order to determine return or error status for the enqueued operation while it is in progress.

### RESTRICTIONS

The asynchronous I/O control buffer ```aiocbp` should be zeroed before the aio_fsync(``) system call to avoid passing bogus context information to the kernel.

Modifications of the Asynchronous I/O Control Block structure after the request has been enqueued, but before the request has completed, are not allowed.

### RETURN VALUES

### ERRORS

The aio_fsync(``) system call will fail if:

[```EAGAIN`]
  The request was not queued because of system resource limitations.

The following conditions may be synchronously detected when the aio_fsync(``) system call is made, or asynchronously, at any time thereafter. If they are detected at call time, aio_fsync(``) returns -1 and sets errno appropriately; otherwise the aio_return(``) system call must be called, and will return -1, and aio_error(``) must be called to determine the actual value that would have been returned in errno.

[```EBADF`]
  The ```aiocbp->aio_fildes` is invalid for writing.

[```EINVAL`]
  This implementation does not support synchronized I/O for this file.

[```EINVAL`]
  The ```op` argument is neither set to ```O_DSYNC` nor ```O_SYNC`.

### SEE ALSO

fcntl(2), fdatasync(2), fsync(2), aio_error(3), aio_read(3), aio_write(3)

### STANDARDS

The aio_fsync(``) system call is expected to conform to the IEEE Std 1003.1-2001 (``POSIX.1'') standard.

### HISTORY

The aio_fsync(``) system call first appeared in NetBSD5.0.