Comment # 13 on bug 1032027 from Stanislav Brabec

I just digged the internet a bit, and probably found a work-around.

After 50 minutes that my system was totally irresponsive and 100% of one CPU
time was consumed by btrfs-cleaner, I tried "btrfs quota disable /" and the
system immediately returned to a normal work.

goblin:~ # btrfs qgroup show /
WARNING: qgroup data inconsistent, rescan recommended
qgroupid         rfer         excl 
--------         ----         ---- 
0/5          16.00KiB     16.00KiB 
0/256        16.00KiB     16.00KiB 
0/258        36.36GiB     36.36GiB 
0/259        16.00KiB     16.00KiB 
0/260        16.93MiB     16.93MiB 
0/261        16.00KiB     16.00KiB 
0/262        60.09MiB     60.09MiB 
0/263       208.97MiB    208.97MiB 
0/264         3.41MiB      3.41MiB 
0/265        16.00KiB     16.00KiB 
0/266         1.68MiB      1.68MiB 
0/267       171.24GiB    481.68MiB 
0/568       207.82GiB      1.33GiB 
0/570       207.89GiB    598.05MiB 
0/580       208.44GiB     40.92MiB 
0/581        16.00KiB     16.00KiB 
0/582       208.48GiB     20.84MiB 
0/608       164.04GiB     76.45MiB 
0/609       163.75GiB     86.62MiB 
0/620       164.38GiB     35.93MiB 
0/623       164.51GiB    207.21MiB 
0/676       171.32GiB    932.00KiB 
0/677       171.32GiB    804.00KiB 
0/678       171.32GiB    672.00KiB 
0/679       171.32GiB    932.00KiB 
0/680       171.32GiB    624.00KiB 
0/681       171.32GiB      1.28MiB 
0/682       171.38GiB    876.00KiB 
0/683       171.38GiB      1.54MiB 
0/685       171.38GiB    596.00KiB 
0/686       171.39GiB      3.06MiB 
1/0         227.40GiB     56.04GiB 
255/581      16.00KiB     16.00KiB 
goblin:~ # btrfs quota disable /
goblin:~ # btrfs qgroup show /
ERROR: can't list qgroups: quotas not enabled