Index: linux-stage/fs/ext4/dir.c
===================================================================
--- linux-stage.orig/fs/ext4/dir.c	2011-03-31 10:35:49.000000000 +0800
+++ linux-stage/fs/ext4/dir.c	2011-04-01 09:33:58.706267179 +0800
@@ -249,19 +249,32 @@
 /*
  * These functions convert from the major/minor hash to an f_pos
  * value.
- *
- * Currently we only use major hash numer.  This is unfortunate, but
- * on 32-bit machines, the same VFS interface is used for lseek and
- * llseek, so if we use the 64 bit offset, then the 32-bit versions of
- * lseek/telldir/seekdir will blow out spectacularly, and from within
- * the ext2 low-level routine, we don't know if we're being called by
- * a 64-bit version of the system call or the 32-bit version of the
- * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
- * cookie.  Sigh.
+ * Whether 64-bit or 32-bit hash value is exported as file pos is
+ * controlled by "64bithash" mount option.
  */
-#define hash2pos(major, minor)	(major >> 1)
-#define pos2maj_hash(pos)	((pos << 1) & 0xffffffff)
-#define pos2min_hash(pos)	(0)
+static inline loff_t hash2pos(struct super_block *sb, __u32 major, __u32 minor)
+{
+	if (test_opt(sb, 64BITHASH))
+		return (((__u64)(major >> 1) << 32) | (__u64)minor);
+	else
+		return (major >> 1);
+}
+
+static inline __u32 pos2maj_hash(struct super_block *sb, loff_t pos)
+{
+	if (test_opt(sb, 64BITHASH))
+		return (((pos >> 32) << 1) & 0xffffffff);
+	else
+		return ((pos << 1) & 0xffffffff);
+}
+
+static inline __u32 pos2min_hash(struct super_block *sb, loff_t pos)
+{
+	if (test_opt(sb, 64BITHASH))
+		return (pos  & 0xffffffff);
+	else
+		return (0);
+}
 
 /*
  * This structure holds the nodes of the red-black tree used to store
@@ -322,15 +335,16 @@
 }
 
 
-static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
+static struct dir_private_info *ext4_htree_create_dir_info(
+        struct super_block *sb, loff_t pos)
 {
 	struct dir_private_info *p;
 
 	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 	if (!p)
 		return NULL;
-	p->curr_hash = pos2maj_hash(pos);
-	p->curr_minor_hash = pos2min_hash(pos);
+	p->curr_hash = pos2maj_hash(sb, pos);
+	p->curr_minor_hash = pos2min_hash(sb, pos);
 	return p;
 }
 
@@ -426,7 +440,7 @@
 		       "null fname?!?\n");
 		return 0;
 	}
-	curr_pos = hash2pos(fname->hash, fname->minor_hash);
+	curr_pos = hash2pos(sb, fname->hash, fname->minor_hash);
 	while (fname) {
 		error = filldir(dirent, fname->name,
 				fname->name_len, curr_pos,
@@ -451,7 +465,7 @@
 	int	ret;
 
 	if (!info) {
-		info = ext4_htree_create_dir_info(filp->f_pos);
+		info = ext4_htree_create_dir_info(inode->i_sb, filp->f_pos);
 		if (!info)
 			return -ENOMEM;
 		filp->private_data = info;
@@ -465,8 +479,8 @@
 		free_rb_tree_fname(&info->root);
 		info->curr_node = NULL;
 		info->extra_fname = NULL;
-		info->curr_hash = pos2maj_hash(filp->f_pos);
-		info->curr_minor_hash = pos2min_hash(filp->f_pos);
+		info->curr_hash = pos2maj_hash(inode->i_sb, filp->f_pos);
+		info->curr_minor_hash = pos2min_hash(inode->i_sb, filp->f_pos);
 	}
 
 	/*
Index: linux-stage/fs/ext4/ext4.h
===================================================================
--- linux-stage.orig/fs/ext4/ext4.h	2011-03-31 10:35:50.000000000 +0800
+++ linux-stage/fs/ext4/ext4.h	2011-04-01 09:33:58.740267284 +0800
@@ -785,6 +785,7 @@
 #define EXT4_MOUNT_JOURNAL_CHECKSUM	0x800000 /* Journal checksums */
 #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT	0x1000000 /* Journal Async Commit */
 #define EXT4_MOUNT_I_VERSION            0x2000000 /* i_version support */
+#define EXT4_MOUNT_64BITHASH		0x4000000 /* export 64-bit name hash */
 #define EXT4_MOUNT_DELALLOC		0x8000000 /* Delalloc support */
 #define EXT4_MOUNT_DATA_ERR_ABORT	0x10000000 /* Abort on file data write */
 #define EXT4_MOUNT_BLOCK_VALIDITY	0x20000000 /* Block validity checking */
Index: linux-stage/fs/ext4/super.c
===================================================================
--- linux-stage.orig/fs/ext4/super.c	2011-03-31 10:35:50.000000000 +0800
+++ linux-stage/fs/ext4/super.c	2011-04-01 09:35:00.251453404 +0800
@@ -1540,7 +1540,7 @@
 	Opt_inode_readahead_blks, Opt_journal_ioprio,
 	Opt_discard, Opt_nodiscard,
 	Opt_mballoc, Opt_bigendian_extents, Opt_force_over_16tb,
-	Opt_no_mbcache,
+	Opt_no_mbcache, Opt_64bithash,
 	Opt_extents, Opt_noextents,
 };
 
@@ -1614,6 +1614,7 @@
 	{Opt_discard, "discard"},
 	{Opt_nodiscard, "nodiscard"},
 	{Opt_no_mbcache, "no_mbcache"},
+	{Opt_64bithash, "64bithash"},
 	{Opt_extents, "extents"},
 	{Opt_noextents, "noextents"},
 	{Opt_err, NULL},
@@ -2092,6 +2093,9 @@
 		case Opt_no_mbcache:
 			set_opt(sbi->s_mount_opt, NO_MBCACHE);
 			break;
+		case Opt_64bithash:
+			set_opt(sbi->s_mount_opt, 64BITHASH);
+			break;
 		default:
 			ext4_msg(sb, KERN_ERR,
 			       "Unrecognized mount option \"%s\" "