Avoid error modification during IAM migration (#8156)

The underlying errors are important, for IAM
requirements and should wait appropriately at
the caller level, this allows for distributed
setups to run properly and not fail prematurely
during startup.

Also additionally fix the onlineDisk counting

cmd/iam-etcd-store.go

@@ -213,7 +213,7 @@ func (ies *IAMEtcdStore) migrateToV1() error {
 		case errConfigNotFound:
 			// Need to migrate to V1.
 		default:
-			return errors.New("corrupt IAM format file")
+			return err
 		}
 	} else {
 		if iamFmt.Version >= iamFormatVersion1 {

cmd/iam-object-store.go

@@ -127,8 +127,8 @@ func (iamOS *IAMObjectStore) migrateUsersConfigToV1(isSTS bool) error {
 		identityPath := pathJoin(basePrefix, user, iamIdentityFile)
 		var cred auth.Credentials
 		if err := iamOS.loadIAMConfig(&cred, identityPath); err != nil {
-			switch err.(type) {
-			case ObjectNotFound:
+			switch err {
+			case errConfigNotFound:
 				// This should not happen.
 			default:
 				// File may be corrupt or network error
@@ -169,7 +169,7 @@ func (iamOS *IAMObjectStore) migrateToV1() error {
 		case errConfigNotFound:
 			// Need to migrate to V1.
 		default:
-			return errors.New("corrupt IAM format file")
+			return err
 		}
 	} else {
 		if iamFmt.Version >= iamFormatVersion1 {

cmd/xl-v1.go

@@ -101,6 +101,7 @@ func getDisksInfo(disks []StorageAPI) (disksInfo []DiskInfo, onlineDisks int, of
 	for _, err := range errs {
 		if err != nil {
 			offlineDisks++
+			continue
 		}
 		onlineDisks++
 	}