Hello, this patch series allows ext4 to do page writeback without having io_end allocated for the cases when block allocation is not required (it is the part of my writepages improvements that didn't get merged in the first round). In such cases io_end is not really necessary (it is really required only when extent conversion has to happen after IO has finished) so just tweak the IO completion code to allow IO submission without io_end allocated. It saves us memory allocation on writeback path - it is not a big deal for performance but it is nice in close-to-ENOMEM situations. The patches have passed xfstests for ext4 and ext3 configurations, specifically I have taken care to verify IO error handling still works. Honza
