xl: Fix feeding NumVersions & SuccessorModTime to lifecycle (#11462)

After recent refactor where lifecycle started to rely on ObjectInfo to
make decisions, it turned out there are some issues calculating
Successor Modtime and NumVersions, hence the lifecycle is not working as
expected in a versioning bucket in some cases.

This commit fixes the behavior.

cmd/xl-storage-format-v2.go

@@ -611,12 +611,13 @@ func (z xlMetaV2) TotalSize() int64 {
 // versions returns error for unexpected entries.
 // showPendingDeletes is set to true if ListVersions needs to list objects marked deleted
 // but waiting to be replicated
-func (z xlMetaV2) ListVersions(volume, path string) (versions []FileInfo, modTime time.Time, err error) {
+func (z xlMetaV2) ListVersions(volume, path string) ([]FileInfo, time.Time, error) {
-	var latestModTime time.Time
+	var versions []FileInfo
-	var latestVersionID string
+	var err error
+
 	for _, version := range z.Versions {
 		if !version.Valid() {
-			return nil, latestModTime, errFileCorrupt
+			return nil, time.Time{}, errFileCorrupt
 		}
 		var fi FileInfo
 		switch version.Type {
@@ -628,27 +629,22 @@ func (z xlMetaV2) ListVersions(volume, path string) (versions []FileInfo, modTim
 			fi, err = version.ObjectV1.ToFileInfo(volume, path)
 		}
 		if err != nil {
-			return nil, latestModTime, err
+			return nil, time.Time{}, err
-		}
-		if fi.ModTime.After(latestModTime) {
-			latestModTime = fi.ModTime
-			latestVersionID = fi.VersionID
 		}
 		versions = append(versions, fi)
 	}
 
-	// We didn't find the version in delete markers so latest version
+	sort.Sort(versionsSorter(versions))
-	// is indeed one of the actual version of the object with data.
+
 	for i := range versions {
-		if versions[i].VersionID != latestVersionID {
+		versions[i].NumVersions = len(versions)
-			continue
+		if i > 0 {
+			versions[i].SuccessorModTime = versions[i-1].ModTime
 		}
-		versions[i].IsLatest = true
-		break
 	}
 
-	sort.Sort(versionsSorter(versions))
+	versions[0].IsLatest = true
-	return versions, latestModTime, nil
+	return versions, versions[0].ModTime, nil
 }
 
 func getModTimeFromVersion(v xlMetaV2Version) time.Time {
@@ -744,8 +740,8 @@ findVersion:
 		// A version is found, fill dynamic fields
 		fi.IsLatest = i == 0
 		fi.NumVersions = len(z.Versions)
-		if i < len(orderedVersions)-1 {
+		if i > 0 {
-			fi.SuccessorModTime = getModTimeFromVersion(orderedVersions[i+1])
+			fi.SuccessorModTime = getModTimeFromVersion(orderedVersions[i-1])
 		}
 		return fi, nil
 	}