Some times ago, trying to reach better performances on my SDD, I followed the wrong suggestion to disable the journal. This solution isn’t really good because I had some data loss and at almost each reboot the system got in fsck.
Yesterday I decided to go back and restore the journal. Each guide I found online was related to non root fs or to boot in maintenance mode. The only thing you need is a ro mountetd fs and usually you fine on internet this command line:
sudo mount -r -o remount /
Which is not enought and you get a busy error message.
The way to go around this issue is to force the remount, so if you want to enable journal:
sudo mount -f -r -o remount /dev/sda6
sudo tune2fs -O has_journal /dev/sda6
Or disable it:
sudo mount -f -r -o remount /dev/sda6
sudo tune2fs -O has_journal /dev/sda6