aio_fsync(2)aio_fsync(2)NAMEaio_fsync - Asynchronously writes changes in a file to permanent stor‐
age
SYNOPSIS
#include <aio.h>
int aio_fsync (
int op,
struct aiocb *aiocbp );
LIBRARY
Asynchronous I/O Library (libaio, libaio_raw)
PARAMETERS
Specifies file or data synchronization. Specifies a pointer to an
aiocb structure. This function uses only the aio_fildes and
aio_sigevent fields of the aiocbp control block.
DESCRIPTION
The aio_fsync function asynchronously causes system buffers containing
a file's modified data to be written to permanent storage. All modi‐
fied data in the file indicated by the file descriptor in the
aio_fildes member of the aiocb structure referenced by the aiocbp argu‐
ment is forced to the synchronized I/O completion state.
The aio_fsync function returns when the synchronization request has
been initiated or queued, even when data cannot be synchronized immedi‐
ately.
If op is O_DSYNC, all currently queued I/O operations are completed as
if by a call to fdatasync. If op is O_SYNC, all currently queued I/O
operations are completed as if by a call to fsync. If the aio_fsync
function fails, outstanding I/O operations are not guaranteed to have
been completed.
If aio_fsync succeeds, only the I/O that was queued at the time of the
call is guaranteed to be synchronized; the completion of subsequent I/O
is not guaranteed.
The aiocbp value may be used as an argument to the aio_error and
aio_return functions to determine the error or return status 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 synchronized, the error status is set to reflect the suc‐
cess or failure of the operation. The aio_sigevent member of the aiocb
structure defines the signal to be generated upon completion of the
operation. If aio_sigevent.sigev_notify equals SIGEV_SIGNAL and
aio_sigevent.sigev_signo is non-zero, a signal will be generated when
all operations have achieved synchronized I/O completion.
RETURN VALUES
Upon successful completion, the aio_fsync function returns a value of 0
(zero). If the aio_fsync function fails, a value of -1 is returned and
errno is set to indicate the error. If aio_fsync fails, outstanding I/O
operations are not guaranteed to have been completed.
ERRORS
If the aio_fsync function fails, errno may be set to one of the follow‐
ing values: The requested asynchronous operation was not queued due to
temporary resource limitations. The aio_fildes member of the aiocb
structure is not a valid file descriptor. A value of op other than
O_DSYNC or O_SYNC was specified.
If any queued I/O operations fail, the aio_fsync function returns error
conditions defined for read and write. The error is returned in the
error status for the asynchronous fsync operation, which can be
retrieved using aio_error.
SEE ALSO
Functions: fdatasync(2), fcntl(2), fsync(2), open(2), read(2), sync(2),
write(2)
Guide to Realtime Programming
aio_fsync(2)