Index: linux-2.6.18-128.1.6/fs/ext4/super.c
===================================================================
--- linux-2.6.18-128.1.6.orig/fs/ext4/super.c
+++ linux-2.6.18-128.1.6/fs/ext4/super.c
@@ -70,6 +70,8 @@ struct page *ext4_zero_page;
 
 struct proc_dir_entry *proc_root_ext4;
 
+static int bigendian_extents;
+
 ext4_fsblk_t ext4_block_bitmap(struct super_block *sb,
 			       struct ext4_group_desc *bg)
 {
@@ -1222,7 +1224,7 @@ enum {
 	Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
 	Opt_grpquota, Opt_extents, Opt_noextents, Opt_i_version,
	Opt_inode_readahead_blks, Opt_journal_ioprio,
-	Opt_iopen, Opt_noiopen, Opt_iopen_nopriv,
+	Opt_iopen, Opt_noiopen, Opt_iopen_nopriv, Opt_bigendian_extents,
 };
 
 static match_table_t tokens = {
@@ -1284,6 +1286,7 @@ static match_table_t tokens = {
	{Opt_auto_da_alloc, "auto_da_alloc=%u"},
	{Opt_auto_da_alloc, "auto_da_alloc"},
	{Opt_noauto_da_alloc, "noauto_da_alloc"},
+	{Opt_bigendian_extents, "bigendian_extents"},
 	{Opt_err, NULL},
 };
 
@@ -1682,6 +1685,9 @@ clear_qf_name:
 				return 0;
 			sbi->s_stripe = option;
 			break;
+		case Opt_bigendian_extents:
+			bigendian_extents = 1;
+			break;
 		default:
 			printk(KERN_ERR
 			       "EXT4-fs: Unrecognized mount option \"%s\" "
@@ -2561,6 +2567,15 @@ static int ext4_fill_super(struct super_
 		goto failed_mount;
 	}
 
+#ifdef __BIG_ENDIAN
+	if (bigendian_extents == 0) {
+		printk(KERN_ERR "EXT4-fs: extents feature is not guaranteed to "
+		       "work on big-endian systems. Use \"bigendian_extents\" "
+		       "mount option to override.\n");
+		goto failed_mount;
+	}
+#endif
+
 	bgl_lock_init(&sbi->s_blockgroup_lock);
 
 	sbi->s_last_alloc_group = -1;