On Thu, Jan 12, 2012 at 12:03:44PM +0100, Lukas Czerner wrote:

+	/* We do not support data journalling with delayed allocation */
+	if (!S_ISREG(inode->i_mode) ||
+	   (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) ||
+	   (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) &&
+	   !test_opt(inode->i_sb, DELALLOC)))
+		return EXT4_INODE_JOURNAL_DATA_MODE;	/* journal data */

It's probably clearer to make avoid the complex boolean expression:

	if (!S_ISREG(inode->i_mode))
		return EXT4_INODE_JOURNAL_DATA_MODE;
	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA))
		return EXT4_INODE_JOURNAL_DATA_MODE;
	if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) &&
	    !test_opt(inode->i_sb, DELALLOC)))
		return EXT4_INODE_JOURNAL_DATA_MODE;

You could combine the first two condiionals:

	if (!S_ISREG(inode->i_mode) ||
	    test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
		return EXT4_INODE_JOURNAL_DATA_MODE;
	if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) &&
	    !test_opt(inode->i_sb, DELALLOC)))
		return EXT4_INODE_JOURNAL_DATA_MODE;

... but combining || and && where someone has to squint and count
parenthesis can be error-prone.  I can look at either of the above two
and understand quickly what's going on.  With what you had (especially
since the identation of !test_opt(...) wasn't quite right, I had to
squint and think for a bit before I convince dmyself it was correct.

Otherwise, looks good!

					- Ted