qcow2: Tweak comments on qcow2_get_persistent_dirty_bitmap_size

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>

1 files changed, 5 insertions, 4 deletions

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 7bf1250..1f38806 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);