A Phoronix reader, Ernest Boyd, sent in an email "Unfortunately another problem appears to exist which more simply produces Ext4 shutdown corruption." From his LaunchPad bug report, it's easy to reproduce this problem:
1. Format and label a target Ext4 partion using Ubuntu 12.04The bug is marked as critical since it results in file-system corruption and is reproducible with the user having made an image of the Ubuntu 12.10 64-bit installation to reproduce. "I can recreate the symptoms of Ext4 filesystem corruption 100% of the time by restoring from the image, booting, logging on and shutting down."
2. Install 64bit 12.10 OS using that target without reformatting it
3. Shut down
4. Boot an alternate copy of Ubuntu
5. Restart selecting the newly installed OS
6. Login then shutdown
6. Boot an alternate copy of Ubuntu
7.Fsck the newly installed OS allowing corrections to be made
Each time the the newly installed OS is executed and then shutdown, even if execution only consists of logging on, a subsequent fsck will FAIL.
As of yet there's no comment by the upstream Linux kernel developers or the Ubuntu kernel folks.