Defragmentation is not much of a problem because of the way Linux filesystems work. However, if your partitions get too full, it does tend to occur. I have recently found out that one of my drives (way too full) was nearly 60% fragmented.
There is not any defragmenter, however, unless you selected the xfs filesystem. Defragmenting XFS is convenient but rather slow (took me 2 hours to defragment 400GB). For all other filesystems, you are doomed to the dump-and-restore method.
But then I found from my dual booted windows that the NTFS drive has become horribly fragmented and Windows cannot defragment the files that I had accessed from Fedora.
This is the first time I have heard anything like this so I don't know. You could try the ntfsprogs package although, in the long run, the most sensible solution would be to get rid of NTFS altogether. As long as MS will insist on pretending that other operating systems do not exist, there will always be inconveniences.