File system corruption
 

I am implementing Multi-User Hibernation in Linux using Suspend2.
The scenario is as :
There are two users using a system, User_A and User_B.
User_A starts the system, carries his work and then hibernates.
User_B starts the system, carries his work and then hibernates.
User_A comes in, resumes his session, and continues his work and then shuts down the system.
User_B comes in, does the same thing.

Now I have achieved this thing for a single user. But when there are multiple users, I face the problem of file-system corruption. This is coz suppose User_A hibernated with /mnt/c unmounted and when User_B started the system (power-on), /mnt/c will get mounted which will wash out the journal of User_A and lead to file-system corruption such as Multiply claimed blocks.

I think I am in catch-22 situation now. Can anyone propose a probable solution to it?
Also one more significant thing, I am able to separate the process as User Space and Kernel Space processes. Take help of this thing while giving your suggestions... :)

First and only thing comes to mind would be to use some form of overlay or versioning FS. No idea if it can be done at all.