How to solve error "Structure needs cleaning on root file system"?

I am using a ubuntu virtual host to host some websites. Sadly, I had some troubles and had to hard-reboot the server and now it seems like the file system is corrupted. Although, I am able to boot and use it, it is not possible to update the system:

root@myserver:~# apt update
Hit:1 http://mirror.scaleway.com/ubuntu zesty InRelease
Hit:2 http://mirror.scaleway.com/ubuntu zesty-updates InRelease                                                                                       
Hit:3 http://mirror.scaleway.com/ubuntu zesty-security InRelease                                                                                      
Hit:4 http://archive.ubuntu.com/ubuntu zesty InRelease                                                                                                
Get:5 http://archive.ubuntu.com/ubuntu zesty-updates InRelease [89.2 kB]                                                                              
Hit:6 http://ppa.launchpad.net/olipo186/git-auto-deploy/ubuntu zesty InRelease                                                          
Hit:7 http://mirror.klaus-uwe.me/mariadb/repo/10.2/ubuntu zesty InRelease                                                               
Get:8 http://archive.ubuntu.com/ubuntu zesty-security InRelease [89.2 kB]           
Fetched 178 kB in 2s (71.9 kB/s)                               
Reading package lists... Error!
E: flAbsPath on /var/lib/dpkg/status failed - realpath (117: Structure needs cleaning)
E: Could not open file  - open (2: No such file or directory)
E: Problem opening 
E: The package lists or status file could not be parsed or opened.

I found some solutions on the web (e.g., (fsck.ext4 /dev/nbd0), but all require to unmount the drive first. But what to do if the root filesystem is affected?

Is it possible to repair a mounted volume using fsck.ext4?

EDIT: I tried to force a check on reboot by creating a forcefsck file in the root file system. It successfully triggered a check, but I still get the same error when I want to update the system. Are there any other options to repair the system?

Solution 1:

sudo touch /forcefsck

and a reboot will force a check on /.