First of all, this is probably a bad sign for the health of your drive, you should look at the dmesg output and SMART diagnostics of the drive. There’s a package called smartmontools or something like that. Also make a backup now if you haven’t yet.
If it’s just the filesystem that’s borked try fsck like that other person said.
Ah right! I always put a new ROM immediately.
There might be ways around this with an overlay fs.