1 files changed, 58 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5a2db612950b..30476daf966e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3960,6 +3960,58 @@ static int ext4_get_sb(struct file_system_type *fs_type, int flags,
         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)
+static struct file_system_type ext2_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "ext2",
+        .get_sb         = ext4_get_sb,
+        .kill_sb        = kill_block_super,
+        .fs_flags       = FS_REQUIRES_DEV,
+};
+
+static inline void register_as_ext2(void)
+{
+        int err = register_filesystem(&ext2_fs_type);
+        if (err)
+                printk(KERN_WARNING
+                       "EXT4-fs: Unable to register as ext2 (%d)\n", err);
+}
+
+static inline void unregister_as_ext2(void)
+{
+        unregister_filesystem(&ext2_fs_type);
+}
+#else
+static inline void register_as_ext2(void) { }
+static inline void unregister_as_ext2(void) { }
+#endif
+
+#if !defined(CONTIG_EXT3_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
+static struct file_system_type ext3_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "ext3",
+        .get_sb         = ext4_get_sb,
+        .kill_sb        = kill_block_super,
+        .fs_flags       = FS_REQUIRES_DEV,
+};
+
+static inline void register_as_ext3(void)
+{
+        int err = register_filesystem(&ext3_fs_type);
+        if (err)
+                printk(KERN_WARNING
+                       "EXT4-fs: Unable to register as ext3 (%d)\n", err);
+}
+
+static inline void unregister_as_ext3(void)
+{
+        unregister_filesystem(&ext3_fs_type);
+}
+#else
+static inline void register_as_ext3(void) { }
+static inline void unregister_as_ext3(void) { }
+#endif
+
 static struct file_system_type ext4_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "ext4",
@@ -3989,11 +4041,15 @@ static int __init init_ext4_fs(void)
         err = init_inodecache();
         if (err)
                 goto out1;
+        register_as_ext2();
+        register_as_ext3();
         err = register_filesystem(&ext4_fs_type);
         if (err)
                 goto out;
         return 0;
 out:
+        unregister_as_ext2();
+        unregister_as_ext3();
         destroy_inodecache();
 out1:
         exit_ext4_xattr();
@@ -4009,6 +4065,8 @@ out4:
 
 static void __exit exit_ext4_fs(void)
 {
+        unregister_as_ext2();
+        unregister_as_ext3();
         unregister_filesystem(&ext4_fs_type);
         destroy_inodecache();
         exit_ext4_xattr();