After OTA update all my data are in shell folder I have Acer Z530 with Lollipop 5.1, kernel 3.10.65+. I have the 16GB version, without external SD Card.

Today I have received an OTA update and after the restart all my data were gone as well as some 7GB of free space missing on the internal storage. When I connected using adb I have found all my data in folder /mnt/shell/emulated but the new data are being stored in /mnt/shell/emulated/0. So far I was able to find that the 0 is the default directory of the owner user. It seems that this update added the multiuser support, but failed to transfer the data.

How can I easily restore my data? Can I just mv everything to the 0 folder?

At this moment I'm pulling the folder to my PC, to have a backup, but I would rather do it correctly.
Using adb shell and mv command I was able to move all data to correct directory. After that, to be sure I did an restart and everything seems to be working correctly.