Why do you think it is corrupt?
The best way to maintain this partition is from a Linux-Live-CD or a Linux-PC. You need BackupMenu or BackupMenu-Multiboot installed to actually access the partition in USB-mode from The PC.
Boot the N900 with keyboard out, choose 'w' from the menu to export all of your internal and external mmc partitions to the PC. Then start a partition manager like gparted choose the second partition of the internal [29,...GB]memory, right click and choose 'check'.
If everything worksout without errors, you are done!
For errors please post here with the complete output.