The tune2fs command can be used in linux to determine the formatting or blocksize used when an ext2 / ext3 / ext4 (?) partition was created.
#/sbin/tune2fs -l /dev/sda1
will return a page of data values concerning the formatting of the ext2/ext3 partition.
Two lines that are of special interest are:
“Block size:” and “Filesystem features:”
which show the block size (in bytes) and the various special features/options used when formatting the partition (such as if the fs has an ext3 journal).