resource eio_sync_file_range ( int $fd , int $offset , int $nbytes , int $flags [, int $pri = EIO_PRI_DEFAULT [, mixed $callback = NULL [, mixed $data = NULL ]]] )
eio_sync_file_range() permits fine control when synchronizing the open file referred to by the file descriptor fd with disk.
eio_sync_file_range() returns request resource on success or FALSE on error.