Merge remote-tracking branch 'remotes/ericb/tags/pull-bitmaps-2020-07-17' into staging

bitmaps patches for 2020-07-17

- improve corner-case of bitmap migration

# gpg: Signature made Fri 17 Jul 2020 16:10:07 BST
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-bitmaps-2020-07-17:
  migration/block-dirty-bitmap: fix add_bitmaps_to_list
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

migration/block-dirty-bitmap.c

@@ -274,7 +274,11 @@ static int add_bitmaps_to_list(BlockDriverState *bs, const char *bs_name)
     DirtyBitmapMigBitmapState *dbms;
     Error *local_err = NULL;
 
-    bitmap = bdrv_dirty_bitmap_first(bs);
+    FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
+        if (bdrv_dirty_bitmap_name(bitmap)) {
+            break;
+        }
+    }
     if (!bitmap) {
         return 0;
     }