As suggested by Jari Ruusu here :

   http://osdir.com/ml/2003/msg00237.html

diff -urN linux-2.4.36/fs/xfs/linux-2.4/xfs_buf.c linux-2.4.36-xfs-aligned/fs/xfs/linux-2.4/xfs_buf.c
--- linux-2.4.36/fs/xfs/linux-2.4/xfs_buf.c	Wed Jun  1 06:28:10 2005
+++ linux-2.4.36-xfs-aligned/fs/xfs/linux-2.4/xfs_buf.c	Sat Nov 29 13:37:13 2008
@@ -1546,10 +1546,10 @@
 	btp->pbr_bdev = bdev;
 	switch (MAJOR(btp->pbr_dev)) {
 	case MD_MAJOR:
+	case LOOP_MAJOR:
 	case EVMS_MAJOR:
 		btp->pbr_flags = PBR_ALIGNED_ONLY;
 		break;
-	case LOOP_MAJOR:
 	case LVM_BLK_MAJOR:
 		btp->pbr_flags = PBR_SECTOR_ONLY;
 		break;