fs/ext3/ext3-exports.c |    3 ++
 fs/ext3/inode.c        |   55 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

Index: linux-2.4.18-p4smp/fs/ext3/ext3-exports.c
===================================================================
--- linux-2.4.18-p4smp.orig/fs/ext3/ext3-exports.c	Thu Nov 27 22:18:40 2003
+++ linux-2.4.18-p4smp/fs/ext3/ext3-exports.c	Thu Nov 27 22:18:40 2003
@@ -9,6 +9,8 @@
 
 int ext3_prep_san_write(struct inode *inode, long *blocks,
 	                int nblocks, loff_t newsize);
+int ext3_map_inode_page(struct inode *inode, struct page *page,
+                        unsigned long *block, int *created, int create);
 
 EXPORT_SYMBOL(ext3_force_commit);
 EXPORT_SYMBOL(ext3_bread);
@@ -18,3 +20,4 @@
 EXPORT_SYMBOL(ext3_xattr_list);
 EXPORT_SYMBOL(ext3_xattr_set);
 EXPORT_SYMBOL(ext3_prep_san_write);
+EXPORT_SYMBOL(ext3_map_inode_page);
Index: linux-2.4.18-p4smp/fs/ext3/inode.c
===================================================================
--- linux-2.4.18-p4smp.orig/fs/ext3/inode.c	Thu Nov 27 22:18:40 2003
+++ linux-2.4.18-p4smp/fs/ext3/inode.c	Thu Nov 27 22:20:36 2003
@@ -3004,3 +3004,80 @@
 		ret = ret2;
 	return ret;
 }
+
+/* copied from fs/buffer.c */
+static void unmap_underlying_metadata(struct buffer_head * bh)
+{
+	struct buffer_head *old_bh;
+
+	old_bh = get_hash_table(bh->b_dev, bh->b_blocknr, bh->b_size);
+	if (old_bh) {
+		mark_buffer_clean(old_bh);
+		wait_on_buffer(old_bh);
+		clear_bit(BH_Req, &old_bh->b_state);
+		__brelse(old_bh);
+	}
+}
+
+int ext3_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;
+        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] = ext3_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 = ext3_writepage_trans_blocks(inode);
+        lock_kernel();
+        handle = ext3_journal_start(inode, needed_blocks);
+        unlock_kernel();
+        if (IS_ERR(handle))
+                return PTR_ERR(handle);
+
+        iblock = page->index * blocks_per_page;
+        for (i = 0; i < blocks_per_page; i++, iblock++) {
+                struct buffer_head bh;
+
+                if (blocks[i] != 0)
+                        continue;
+
+                rc = ext3_get_block_handle(handle, inode, iblock, &bh, 1);
+                if (rc) {
+                        printk(KERN_INFO "ext3_map_inode_page: error %d "
+                               "allocating block %ld\n", rc, iblock);
+                        goto out;
+                }
+		/* 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(&bh))
+                        unmap_underlying_metadata(&bh);
+                blocks[i] = bh.b_blocknr;
+		if (created)
+			created[i] = 1;
+        }
+
+ out:
+	lock_kernel();
+	ext3_journal_stop(handle, inode);
+	unlock_kernel();
+        return rc;
+}