You left your file type out of this line:
/dev/sda1...../data...defaults...1 2 .
I assume you made a mistake in copying it.
Did you run fsck? Remember that you don't have to mount the partition to check it. Just fsck /dev/sda1
Try mounting it with this command:
mount -t ext2 /dev/sda1 /data
I hope this helps.