From: Paolo Bonzini <pbonzini@redhat.com>

Any data that is returned by read may be stale already, the bitmap
has to be cleared before issuing the read.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170525163225.29954-16-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 migration/block.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/migration/block.c b/migration/block.c
index 9e9f031..8fe484e 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -536,6 +536,8 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
             } else {
                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
             }
+            bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, sector, nr_sectors);
+
             blk = g_new(BlkMigBlock, 1);
             blk->buf = g_malloc(BLOCK_SIZE);
             blk->bmds = bmds;
@@ -568,7 +570,6 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
                 g_free(blk);
             }
 
-            bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, sector, nr_sectors);
             sector += nr_sectors;
             bmds->cur_dirty = sector;
 
-- 
2.9.4