drive and blockdev backup cannot use readonly bitmaps, because the
sync=incremental mechanism actually edits the bitmaps on success.

If you really want to do this operation, use a copied bitmap.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
---
 blockdev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 455ab806b2..c6c7a64bfc 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3533,7 +3533,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup, JobTxn *txn,
             bdrv_unref(target_bs);
             goto out;
         }
-        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
+        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_DEFAULT, errp)) {
             goto out;
         }
     }
@@ -3643,7 +3643,7 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
             error_setg(errp, "Bitmap '%s' could not be found", backup->bitmap);
             goto out;
         }
-        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
+        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_DEFAULT, errp)) {
             goto out;
         }
     }
-- 
2.17.2