Improve savevm consistency by flushing pending AIO before saving.

Index: qemu/vl.c
===================================================================
--- qemu.orig/vl.c	2006-09-03 10:45:28.000000000 +0000
+++ qemu/vl.c	2006-09-03 11:06:13.000000000 +0000
@@ -4551,6 +4551,17 @@
         return;
     }

+    /* Flush pending AIO before saving */
+    ret = qemu_aio_poll();
+    if (ret) {
+        qemu_aio_wait_start();
+        do {
+            qemu_aio_wait();
+            ret = qemu_aio_poll();
+        } while (ret);
+        qemu_aio_wait_end();
+    }
+
     saved_vm_running = vm_running;
     vm_stop(0);

Index: qemu/block-raw.c
===================================================================
--- qemu.orig/block-raw.c	2006-09-03 11:00:39.000000000 +0000
+++ qemu/block-raw.c	2006-09-03 11:03:40.000000000 +0000
@@ -206,10 +206,12 @@
#endif
}

-void qemu_aio_poll(void)
+int qemu_aio_poll(void)
{
     RawAIOCB *acb, **pacb;
-    int ret;
+    int ret, aios_active;
+
+    aios_active = 0;

     for(;;) {
         pacb = &first_aio;
@@ -240,11 +242,14 @@
                 qemu_aio_release(acb);
                 break;
             } else {
+                /* aio still active */
                 pacb = &acb->next;
+                aios_active = 1;
             }
         }
     }
- the_end: ;
+ the_end:
+    return aios_active;
}

/* wait until at least one AIO was handled */
Index: qemu/vl.h
===================================================================
--- qemu.orig/vl.h	2006-09-03 11:00:43.000000000 +0000
+++ qemu/vl.h	2006-09-03 11:04:10.000000000 +0000
@@ -579,7 +579,7 @@
void bdrv_aio_cancel(BlockDriverAIOCB *acb);

void qemu_aio_init(void);
-void qemu_aio_poll(void);
+int qemu_aio_poll(void);
void qemu_aio_wait_start(void);
void qemu_aio_wait(void);
void qemu_aio_wait_end(void);