root@lin:~# time btrfsck /dev/sda1
found 351798788096 bytes used err is 0
total csum bytes: 338904032
total tree bytes: 4761059328
total fs tree bytes: 4121874432
btree space waste bytes: 1261806254
file data blocks allocated: 347037728768
 referenced 346944118784
Btrfs Btrfs v0.19

real	52m46.138s
user	15m8.060s
sys	0m45.660s