Turn on extents feature by default in ext4 filesystem. User could use
-o noextents to turn it off.

Signed-Off-By: Mingming Cao <cmm@us.ibm.com>

Index: linux-2.6.22-rc1/fs/ext4/super.c
===================================================================
--- linux-2.6.22-rc1.orig/fs/ext4/super.c	2007-05-15 16:25:38.000000000 -0700
+++ linux-2.6.22-rc1/fs/ext4/super.c	2007-05-15 16:25:41.000000000 -0700
@@ -1548,6 +1548,12 @@
 
 	set_opt(sbi->s_mount_opt, RESERVATION);
 
+	/*
+	 * turn on extents feature by default in ext4 filesystem
+	 * User -o noextents to turn it off
+	 */
+	set_opt (sbi->s_mount_opt, EXTENTS);
+
 	if (!parse_options ((char *) data, sb, &journal_inum, &journal_devnum,
 			    NULL, 0))
 		goto failed_mount;