Instead of relying on the slower LVM stacking, use ext4's new encryption feature to separately encrypt each user's home directory: See http://lwn.net/Articles/639427/ for details
(In reply to Bastien Nocera from comment #0) > Instead of relying on the slower LVM stacking First, disk encryption has nothing to do with LVM as of now (device-mapper and lvm2 are not in equivalence relation), second, do you have any numbers to prove the slowness claim? The referenced article lacks these numbers IIRC. From the same article, purpose of ext4 encryption and goals of that feature aim different target than the speed in a first place. Especially authentication is stressed out but missing so far from short-term TODO list
This bug appears to have been reported against 'rawhide' during the Fedora 23 development cycle. Changing version to '23'. (As we did not run this process for some time, it could affect also pre-Fedora 23 development cycle bugs. We are very sorry. It will help us with cleanup during Fedora 23 End Of Life. Thank you.) More information and reason for this action is here: https://fedoraproject.org/wiki/BugZappers/HouseKeeping/Fedora23
There's nothing here to backup the claims, as noted in comment 1, and there's not even support for this in Fedora's utilities.