close all the block drivers before the qemu process exits

This patch calls the close handler of the block driver before the qemu
process exits.

This is necessary because the sheepdog block driver releases the lock
of VM images in the close handler.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -648,6 +648,15 @@ void bdrv_close(BlockDriverState *bs)
     }
 }
 
+void bdrv_close_all(void)
+{
+    BlockDriverState *bs;
+
+    QTAILQ_FOREACH(bs, &bdrv_states, list) {
+        bdrv_close(bs);
+    }
+}
+
 void bdrv_delete(BlockDriverState *bs)
 {
     /* remove from list, if necessary */

block.h

@@ -123,6 +123,7 @@ BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
 /* Ensure contents are flushed to disk.  */
 void bdrv_flush(BlockDriverState *bs);
 void bdrv_flush_all(void);
+void bdrv_close_all(void);
 
 int bdrv_has_zero_init(BlockDriverState *bs);
 int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,

vl.c

@@ -1991,6 +1991,7 @@ static void main_loop(void)
             vm_stop(r);
         }
     }
+    bdrv_close_all();
     pause_all_vcpus();
 }