heal legacy objects when versioning is enabled after upgrade (#13671)

legacy objects in 'xl.json' after upgrade, should have
following sequence of events - bucket should have versioning
enabled and the object should have been overwritten with
another version of an object.

this situation was not handled, which would lead to older
objects to stay perpetually with "legacy" dataDir, however
these objects were readable by all means - there weren't
converted to newer format.

This PR fixes this situation properly.

cmd/xl-storage-format-utils.go

@@ -18,9 +18,11 @@
 package cmd
 
 import (
+	"fmt"
 	"sort"
 
 	jsoniter "github.com/json-iterator/go"
+	"github.com/minio/minio/internal/logger"
 )
 
 // versionsSorter sorts FileInfo slices by version.
@@ -121,15 +123,17 @@ func getFileInfo(xlMetaBuf []byte, volume, path, versionID string, data bool) (F
 	xlMeta := &xlMetaV1Object{}
 	var json = jsoniter.ConfigCompatibleWithStandardLibrary
 	if err := json.Unmarshal(xlMetaBuf, xlMeta); err != nil {
+		logger.LogIf(GlobalContext, fmt.Errorf("unable to unmarshal json object: %v", err))
 		return FileInfo{}, errFileCorrupt
 	}
 
 	fi, err := xlMeta.ToFileInfo(volume, path)
-	if err == errFileNotFound && versionID != "" {
-		return fi, errFileVersionNotFound
+	if err != nil {
+		return FileInfo{}, err
 	}
-	fi.IsLatest = true // No versions so current version is latest.
+
 	fi.XLV1 = true     // indicates older version
+	fi.IsLatest = true // No versions so current version is latest.
 	return fi, err
 }