block/dirty-bitmaps: disallow busy bitmaps as merge source

We didn't do any state checking on source bitmaps at all,
so this adds inconsistent and busy checks. readonly is
allowed, so you can still copy a readonly bitmap to a new
destination to use it for operations like drive-backup.

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: 20190301191545.8728-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 6170f3a..2139354 100644 (file)
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -825,6 +825,9 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
         goto out;
     }
 
+    if (bdrv_dirty_bitmap_check(src, BDRV_BITMAP_ALLOW_RO, errp)) {
+        goto out;
+    }
 
     if (!hbitmap_can_merge(dest->bitmap, src->bitmap)) {
         error_setg(errp, "Bitmaps are incompatible and can't be merged");