| .TH aio_fsync 3 2002-09-12 "Linux 2.4" Linux AIO" |
| .SH NAME |
| aio_fsync \- Synchronize a file's complete in-core state with that on disk |
| .SH SYNOPSYS |
| .nf |
| .B #include <errno.h> |
| .sp |
| .br |
| .B #include <aio.h> |
| .sp |
| .br |
| .BI "int aio_fsync (int op, struct aiocb aiocbp)" |
| .fi |
| .SH DESCRIPTION |
| .PP |
| 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). Instead POSIX.1b defines two |
| functions which will help with most kinds of consistency. |
| .PP |
| The |
| .IR aio_fsync |
| and |
| .IR "aio_fsync64" |
| functions are only available |
| if the symbol |
| .IR "_POSIX_SYNCHRONIZED_IO" |
| is defined in |
| .I unistd.h |
| . |
| |
| Calling this function forces all I/O operations operating queued at the |
| time of the function call operating on the file descriptor |
| .IR "aiocbp->aio_fildes" |
| into the synchronized I/O completion state . The |
| .IR "aio_fsync" |
| function returns |
| immediately but the notification through the method described in |
| .IR "aiocbp->aio_sigevent" |
| 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. |
| |
| If |
| .IR "op" |
| is |
| .IR "O_DSYNC" |
| the synchronization happens as with a call |
| to |
| .IR "fdatasync" |
| . Otherwise |
| .IR "op" |
| should be |
| .IR "O_SYNC" |
| and |
| the synchronization happens as with |
| .IR "fsync" |
| . |
| |
| As long as the synchronization has not happened, a call to |
| .IR "aio_error" |
| with the reference to the object pointed to by |
| .IR "aiocbp" |
| returns |
| .IR "EINPROGRESS" |
| . Once the synchronization is |
| done |
| .IR "aio_error" |
| return |
| .IR 0 |
| if the synchronization was not |
| successful. Otherwise the value returned is the value to which the |
| .IR "fsync" |
| or |
| .IR "fdatasync" |
| function would have set the |
| .IR "errno" |
| variable. In this case nothing can be assumed about the |
| consistency for the data written to this file descriptor. |
| |
| .SH "RETURN VALUES" |
| The return value of this function is |
| .IR 0 |
| if the request was |
| successfully enqueued. Otherwise the return value is |
| .IR -1 |
| and |
| .IR "errno". |
| .SH ERRORS |
| .TP |
| .B EAGAIN |
| The request could not be enqueued due to temporary lack of resources. |
| .TP |
| .B EBADF |
| The file descriptor |
| .IR "aiocbp->aio_fildes" |
| is not valid or not open |
| for writing. |
| .TP |
| .B EINVAL |
| The implementation does not support I/O synchronization or the |
| .IR "op" |
| parameter is other than |
| .IR "O_DSYNC" |
| and |
| .IR "O_SYNC" |
| . |
| .TP |
| .B ENOSYS |
| This function is not implemented. |
| .PP |
| When the sources are compiled with |
| .IR "_FILE_OFFSET_BITS == 64" |
| this |
| function is in fact |
| .IR "aio_return64" |
| since the LFS interface |
| transparently replaces the normal implementation. |
| .SH "SEE ALSO" |
| .BR aio(3), |
| .BR aio_cancel(3), |
| .BR aio_cancel64(3), |
| .BR aio_error(3), |
| .BR aio_error64(3), |
| .BR aio_fsync64(3), |
| .BR aio_init(3), |
| .BR aio_read(3), |
| .BR aio_read64(3), |
| .BR aio_return(3), |
| .BR aio_return64(3), |
| .BR aio_suspend(3), |
| .BR aio_suspend64(3), |
| .BR aio_write(3), |
| .BR aio_write64(3), |
| .BR errno(3), |
