From: Eric Blake <eblake@redhat.com>

For now, we don't have persistent bitmaps in any other formats, but
that might not be true in the future.  Make it obvious that our
incoming parameter is not necessarily a qcow2 image, and therefore is
limited to just the bdrv_dirty_bitmap_* API calls (rather than probing
into qcow2 internals).

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200608190821.3293867-1-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-bitmap.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 7bf12502da..1f38806ca6 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1757,19 +1757,20 @@ bool qcow2_supports_persistent_dirty_bitmap(BlockDriverState *bs)
 }
 
 /*
- * Compute the space required for bitmaps in @bs.
+ * Compute the space required to copy bitmaps from @in_bs.
  *
  * The computation is based as if copying to a new image with the
- * given @cluster_size, which may differ from the cluster size in @bs.
+ * given @cluster_size, which may differ from the cluster size in
+ * @in_bs; in fact, @in_bs might be something other than qcow2.
  */
-uint64_t qcow2_get_persistent_dirty_bitmap_size(BlockDriverState *bs,
+uint64_t qcow2_get_persistent_dirty_bitmap_size(BlockDriverState *in_bs,
                                                 uint32_t cluster_size)
 {
     uint64_t bitmaps_size = 0;
     BdrvDirtyBitmap *bm;
     size_t bitmap_dir_size = 0;
 
-    FOR_EACH_DIRTY_BITMAP(bs, bm) {
+    FOR_EACH_DIRTY_BITMAP(in_bs, bm) {
         if (bdrv_dirty_bitmap_get_persistence(bm)) {
             const char *name = bdrv_dirty_bitmap_name(bm);
             uint32_t granularity = bdrv_dirty_bitmap_granularity(bm);
-- 
2.25.4