pcsx2:freebsd: Disable aio use on FreeBSD 10.3 and earlier

A FreeBSD 10.3 user (meowthink) reported to me that games were not
working properly on their system. After some investigation, it was
discovered that aio was buggy on their setup. There's also bug reports
for other applications that involve aio too.

Workaround the issue by using a normal read and disabling the use of aio
on FreeBSD 10.3 and earlier. It'll remain enabled on FreeBSD 11.0 in the
hope that the aio issue has since been fixed.

pcsx2/Darwin/DarwinFlatFileReader.cpp

@@ -20,7 +20,14 @@
 #warning Tested on FreeBSD, not OS X. Be very afraid.
 #endif
 
-//FlatFileReader::FlatFileReader(void)
+// The aio module has been reported to cause issues with FreeBSD 10.3, so let's
+// disable it for 10.3 and earlier and hope FreeBSD 11 and onwards is fine.
+// Note: It may be worth checking whether aio provides any performance benefit.
+#if defined(__FreeBSD__) && __FreeBSD__ < 11
+#define DISABLE_AIO
+#warning AIO has been disabled.
+#endif
+
 FlatFileReader::FlatFileReader(bool shareWrite) : shareWrite(shareWrite)
 {
 	m_blocksize = 2048;
@@ -54,6 +61,11 @@ void FlatFileReader::BeginRead(void* pBuffer, uint sector, uint count)
 
 	u32 bytesToRead = count * m_blocksize;
 
+#if defined(DISABLE_AIO)
+	m_aiocb.aio_nbytes = pread(m_fd, pBuffer, bytesToRead, offset);
+	if (m_aiocb.aio_nbytes != bytesToRead)
+		m_aiocb.aio_nbytes = -1;
+#else
 	m_aiocb = {0};
 	m_aiocb.aio_fildes = m_fd;
 	m_aiocb.aio_offset = offset;
@@ -71,11 +83,16 @@ void FlatFileReader::BeginRead(void* pBuffer, uint sector, uint count)
 #endif
 		return;
 	}
+#endif
 	m_read_in_progress = true;
 }
 
 int FlatFileReader::FinishRead(void)
 {
+#if defined(DISABLE_AIO)
+	m_read_in_progress = false;
+	return m_aiocb.aio_nbytes == (size_t)-1 ? -1: 1;
+#else
 	struct aiocb *aiocb_list[] = {&m_aiocb};
 
 	while (aio_suspend(aiocb_list, 1, nullptr) == -1)
@@ -84,11 +101,14 @@ int FlatFileReader::FinishRead(void)
 
 	m_read_in_progress = false;
 	return aio_return(&m_aiocb) == -1? -1: 1;
+#endif
 }
 
 void FlatFileReader::CancelRead(void)
 {
+#if !defined(DISABLE_AIO)
 	aio_cancel(m_fd, &m_aiocb);
+#endif
 	m_read_in_progress = false;
 }