NAME [Toc] [Back]
aio_fsync() - force outstanding asynchronous operations on a file to
the synchronized state
SYNOPSIS [Toc] [Back]
int aio_fsync(int op, struct aiocb *aiocbp);
DESCRIPTION [Toc] [Back]
The aio_fsync() function asynchronously forces all I/O operations that
are enqueued at the time of the call for the file or device referenced
by aiocbp->aio_fildes to the synchronized I/O state. The function
call returns when the synchronization request has been enqueued to the
file or device (even when the data cannot be synchronized
Successful completion of the aio_fsync() request indicates that all
modified data for aiocbp->fildes has been moved to a permanent storage
device. The aio_fsync() function affects only those asynchronous I/O
operations enqueued at the time of the call. Subsequently enqueued
operations are not included in the synchronizing operation.
The aio_fsync() function supports synchronized I/O for regular files,
block special files, and character special files.
If the op is O_DSYNC, all currently enqueued asynchronous I/O
operations for aiocbp->fildes are completed as if by a call to
fdatasync(). All data is forced to permanent storage but the metadata
(such as modification times) for the file descriptor is not
necessarily updated. If the op is O_SYNC, all currently enqueued
asynchronous I/O operations for aiocbp->fildes are completed as if by
a call to fsync(). All data is forced to permanent storage and the
file descriptor metadata is updated.
If an aio_fsync() request is issued for a file when there is already a
pending aio_fsync() request, the first request is treated as though it
were part of the second, and the second request will not complete
until the first has completed.
The aio_fsync() function returns when the fsync request has been
enqueued for the referenced file or device. The aio_error() and
aio_return() functions must be used to retrieve the status of the
synchronization operation via the aiocb referenced by aiocbp. The
status returned will be EINPROGRESS until the last operation addressed
by the initial request completes. If all operations complete
successfully, the error status will be 0 (zero). Otherwise, the error
status will be the error status that will be returned for the read or
write operation that failed.
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If aiocbp->aio_sigevent is a valid signal event structure, then the
designated signal will be delivered when the requested synchronization
operation completes, either when all subject requests have completed
successfully or when any one of the requests has failed.
To use this function, link in the realtime library by specifying -lrt
on the compiler or linker command line.
RETURN VALUE [Toc] [Back]
If the aio_fsync() function fails, -1 is returned and errno is set to
indicate the error.
ERRORS [Toc] [Back]
If aio_fsync() detects one of the following error conditions, errno is
set to the indicated value:
[EAGAIN] The request could not be queued because a perprocess
or system-wide limit on asynchronous I/O
operations or asynchronous threads would have been
[EBADF] The aiocbp->aio_fildes is not a valid file
descriptor open for writing.
[EINVAL] Synchronized I/O is not supported for the file
specified by aiocbp->aio_fildes.
[EINVAL] The aiocb->aio_sigevent is not a valid address in
the process virtual address space.
[EINVAL] The parameters of the indicated sigevent in
aiocb->aio_sigevent are invalid.
SEE ALSO [Toc] [Back]
aio_cancel(2), aio_error(2), aio_read(2), aio_return(2),
aio_suspend(2), aio_write(2), fdatasync(2), fsync(2), lio_listio(2),
read(2), write(2), aio(5).
STANDARDS CONFORMANCE [Toc] [Back]
aio_fsync(): POSIX Realtime Extensions, IEEE Std 1003.1b
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