Index: linux-2.6.18.i386/fs/ext4/inode.c
===================================================================
--- linux-2.6.18.i386.orig/fs/ext4/inode.c
+++ linux-2.6.18.i386/fs/ext4/inode.c
@@ -3666,3 +3666,66 @@ out_unlock:
 	unlock_page(page);
 	return ret;
 }
+
+int ext4_map_inode_page(struct inode *inode, struct page *page,
+			unsigned long *blocks, int *created, int create)
+{
+	unsigned int blocksize, blocks_per_page;
+	unsigned long iblock;
+	struct buffer_head dummy;
+	void *handle;
+	int i, rc = 0, failed = 0, needed_blocks;
+
+	blocksize = inode->i_sb->s_blocksize;
+	blocks_per_page = PAGE_SIZE >> inode->i_sb->s_blocksize_bits;
+	iblock = page->index * blocks_per_page;
+
+	for (i = 0; i < blocks_per_page; i++, iblock++) {
+		blocks[i] = ext4_bmap(inode->i_mapping, iblock);
+		if (blocks[i] == 0) {
+			failed++;
+			if (created)
+				created[i] = -1;
+		} else if (created) {
+			created[i] = 0;
+		}
+	}
+
+	if (failed == 0 || create == 0)
+		return 0;
+
+	needed_blocks = ext4_writepage_trans_blocks(inode);
+	handle = ext4_journal_start(inode, needed_blocks);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	iblock = page->index * blocks_per_page;
+	for (i = 0; i < blocks_per_page; i++, iblock++) {
+		if (blocks[i] != 0)
+			continue;
+
+		rc = ext4_get_blocks_handle(handle, inode, iblock, 1, &dummy, 1, 1);
+		if (rc < 0) {
+			printk(KERN_INFO "ext4_map_inode_page: error reading "
+					"block %ld\n", iblock);
+			goto out;
+		} else {
+			if (rc > 1)
+				WARN_ON(1);
+			rc = 0;
+		}
+		/* Unmap any metadata buffers from the block mapping, to avoid
+		 * data corruption due to direct-write from Lustre being
+		 * clobbered by a later flush of the blockdev metadata buffer.*/
+		if (buffer_new(&dummy))
+			unmap_underlying_metadata(dummy.b_bdev,
+					dummy.b_blocknr);
+		blocks[i] = dummy.b_blocknr;
+		if (created)
+			created[i] = 1;
+	}
+
+out:
+	ext4_journal_stop(handle);
+	return rc;
+}
Index: linux-2.6.18.i386/fs/ext4/super.c
===================================================================
--- linux-2.6.18.i386.orig/fs/ext4/super.c
+++ linux-2.6.18.i386/fs/ext4/super.c
@@ -3498,6 +3498,10 @@ static void __exit exit_ext4_fs(void)
 	__free_page(ext4_zero_page);
 }
 
+int ext4_map_inode_page(struct inode *inode, struct page *page,
+			unsigned long *blocks, int *created, int create);
+EXPORT_SYMBOL(ext4_map_inode_page);
+
 MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
 MODULE_DESCRIPTION("Fourth Extended Filesystem with extents");
 MODULE_LICENSE("GPL");