diff --git a/mercurial/filelog.py b/mercurial/filelog.py
--- a/mercurial/filelog.py
+++ b/mercurial/filelog.py
@@ -81,7 +81,7 @@ class filelog(object):
     def iscensored(self, rev):
         return self._revlog.iscensored(rev)
 
-    # Used by verify.
+    # Used by repo upgrade, verify.
     def rawsize(self, rev):
         return self._revlog.rawsize(rev)
 
diff --git a/mercurial/upgrade.py b/mercurial/upgrade.py
--- a/mercurial/upgrade.py
+++ b/mercurial/upgrade.py
@@ -491,10 +491,7 @@ def _copyrevlogs(ui, srcrepo, dstrepo, t
         for path in rl.files():
             datasize += rl.opener.stat(path).st_size
 
-        idx = rl.index
-        for rev in rl:
-            e = idx[rev]
-            rawsize += e[2]
+        rawsize += sum(map(rl.rawsize, iter(rl)))
 
         srcsize += datasize
         srcrawsize += rawsize