# ls -l
insgesamt 103960
-rw-rw-rw-. 1 500 nobody 10592048  4. Sep 2013  01-In This Light and on This Evening.mp3
-rw-rw-rw-. 1 500 nobody 15405893  4. Sep 2013  02-Bricks and Mortar.mp3
-rw-rw-rw-. 1 500 nobody 13135330  4. Sep 2013  03-Papillon.mp3
-rw-rw-rw-. 1 500 nobody 11316163  4. Sep 2013  04-You Don't Know Love.mp3
-rw-rw-rw-. 1 500 nobody 11546040  4. Sep 2013  05-The Big Exit.mp3
-rw-rw-rw-. 1 500 nobody 11375722  4. Sep 2013  06-The Boxer.mp3
-rw-rw-rw-. 1 500 nobody 11831169  4. Sep 2013  07-Like Treasure.mp3
-rw-rw-rw-. 1 500 nobody 11891773  4. Sep 2013  08-Eat Raw Meat = Blood Drool.mp3
-rw-rw-rw-. 1 500 nobody  9247137  4. Sep 2013  09-Walk the Fleet Road.mp3
-rw-rw-rw-. 1 500 nobody    94735  4. Sep 2013  cover.jpg

# filefrag *
01-In This Light and on This Evening.mp3: 12 extents found
02-Bricks and Mortar.mp3: 2 extents found
03-Papillon.mp3: 2 extents found
04-You Don't Know Love.mp3: 2 extents found
05-The Big Exit.mp3: 2 extents found
06-The Boxer.mp3: 6 extents found
07-Like Treasure.mp3: 2 extents found
08-Eat Raw Meat = Blood Drool.mp3: 4 extents found
09-Walk the Fleet Road.mp3: 4 extents found
cover.jpg: 1 extent found

# btrfs fi defrag -v -f  01-In\ This\ Light\ and\ on\ This\ Evening.mp3
01-In This Light and on This Evening.mp3
Btrfs v3.14

# filefrag 01-In\ This\ Light\ and\ on\ This\ Evening.mp3
01-In This Light and on This Evening.mp3: 12 extents found