block: mark blocks dirty on coroutine write completion

The aio write operation marks blocks dirty when the write operation
completes.  The coroutine write operation marks blocks dirty before
issuing the write operation.

It seems safest to mark the block dirty when the operation completes so
that anything tracking dirty blocks will not act before the change has
been made to the image file.

Make the coroutine write operation dirty blocks on write completion.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block.c

@@ -1311,6 +1311,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
     int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
     BlockDriver *drv = bs->drv;
+    int ret;
 
     if (!bs->drv) {
         return -ENOMEDIUM;
@@ -1322,6 +1323,8 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
         return -EIO;
     }
 
+    ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
+
     if (bs->dirty_bitmap) {
         set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
     }
@@ -1330,7 +1333,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
         bs->wr_highest_sector = sector_num + nb_sectors - 1;
     }
 
-    return drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
+    return ret;
 }
 
 int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,