ext4: Do not override ext2 or ext3 if built they are built as modules

The CONFIG_EXT4_USE_FOR_EXT23 option must not try to take over the
ext2 or ext3 file systems if the those file system drivers are
configured to be built as mdoules.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 2b13dcf..8b58a14 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3964,7 +3964,7 @@
 	return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super,mnt);
 }
 
-#if !defined(CONTIG_EXT2_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
+#if !defined(CONTIG_EXT2_FS) && !defined(CONFIG_EXT2_FS_MODULE) && defined(CONFIG_EXT4_USE_FOR_EXT23)
 static struct file_system_type ext2_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "ext2",
@@ -3990,7 +3990,7 @@
 static inline void unregister_as_ext2(void) { }
 #endif
 
-#if !defined(CONTIG_EXT3_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
+#if !defined(CONTIG_EXT3_FS) && !defined(CONFIG_EXT3_FS_MODULE) && defined(CONFIG_EXT4_USE_FOR_EXT23)
 static struct file_system_type ext3_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "ext3",