As we've told you, some space is reserved for the superuser on Unix filesystems.. like EXT2 and FFS.
The Windows ext2 driver you're using obviously assumes the role of the superuser (..root) and has full access to the capacity of the partition.
Just because
df(1) on OpenBSD claims 0 bytes of available space, doesn't mean the disk is full.. and even if it was full.. nothing is harmed.
If you're worried that the file was damaged during the copy, you could painfully attempt to hash the file with MD5 or SHA and compare them.. but it's more likely you're just on mental information overload.. don't worry.. you'll become familiar with it all eventually.