===================================================================
Index: linux-2.6.27-rc1/fs/ext4/extents.c
===================================================================

--- linux-2.6.27-rc1.orig/fs/ext4/extents.c	2008-08-11 22:25:39.000000000 -0700
+++ linux-2.6.27-rc1/fs/ext4/extents.c	2008-08-11 22:25:55.000000000 -0700

@@ -2799,7 +2799,7 @@ void ext4_ext_truncate(struct inode *ino
 	/*
 	 * probably first extent we're gonna free will be last in block
 	 */
-	err = ext4_writepage_trans_blocks(inode) + 3;
+	err = ext4_writepage_trans_blocks(inode);
 	handle = ext4_journal_start(inode, err);
 	if (IS_ERR(handle))
 		return;

@@ -2951,10 +2951,9 @@ long ext4_fallocate(struct inode *inode,
 	max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
 							- block;
 	/*
-	 * credits to insert 1 extent into extent tree + buffers to be able to
-	 * modify 1 super block, 1 block bitmap and 1 group descriptor.
+	 * credits to insert 1 extent into extent tree
 	 */
-	credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
+	credits = ext4_data_trans_blocks(inode, max_blocks);

 	mutex_lock(&inode->i_mutex);
 retry:
 	while (ret >= 0 && ret < max_blocks) {
Index: linux-2.6.27-rc1/fs/ext4/inode.c
===================================================================

--- linux-2.6.27-rc1.orig/fs/ext4/inode.c	2008-08-11 22:18:31.000000000 -0700
+++ linux-2.6.27-rc1/fs/ext4/inode.c	2008-08-11 22:25:55.000000000 -0700

@@ -1041,18 +1041,6 @@ static void ext4_da_update_reserve_space
 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 }

-/* Maximum number of blocks we map for direct IO at once. */
-#define DIO_MAX_BLOCKS 4096
-/*
- * Number of credits we need for writing DIO_MAX_BLOCKS:
- * We need sb + group descriptor + bitmap + inode -> 4
- * For B blocks with A block pointers per block we need:
- * 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
- * If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
- */
-#define DIO_CREDITS 25
-
-
 /*
  * The ext4_get_blocks_wrap() function try to look up the requested blocks,
  * and returns if the blocks are already mapped.

@@ -1164,19 +1152,23 @@ int ext4_get_blocks_wrap(handle_t *handl
 	return retval;
 }

+/* Maximum number of blocks we map for direct IO at once. */
+#define DIO_MAX_BLOCKS 4096
+
 static int ext4_get_block(struct inode *inode, sector_t iblock,
 			struct buffer_head *bh_result, int create)
 {
 	handle_t *handle = ext4_journal_current_handle();
 	int ret = 0, started = 0;
 	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+	int dio_credits;

 	if (create && !handle) {
 		/* Direct IO write... */
 		if (max_blocks > DIO_MAX_BLOCKS)
 			max_blocks = DIO_MAX_BLOCKS;
-		handle = ext4_journal_start(inode, DIO_CREDITS +
-			      2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
+		dio_credits = ext4_data_trans_blocks(inode, max_blocks);
+		handle = ext4_journal_start(inode, dio_credits);

 		if (IS_ERR(handle)) {
 			ret = PTR_ERR(handle);
 			goto out;

@@ -2222,7 +2214,7 @@ static int ext4_da_writepage(struct page
  * for DIO, writepages, and truncate
  */
 #define EXT4_MAX_WRITEBACK_PAGES      DIO_MAX_BLOCKS
-#define EXT4_MAX_WRITEBACK_CREDITS    DIO_CREDITS
+#define EXT4_MAX_WRITEBACK_CREDITS    25

 static int ext4_da_writepages(struct address_space *mapping,
 				struct writeback_control *wbc)

@@ -4429,7 +4421,8 @@ static int ext4_writeblocks_trans_credit

 /*