disk-fill:fallocate failed no space left on devide

[sunny-xiao]

when i set a experiment like: ‘chaosd attack disk fill -p /home -s 30G’,it returns "fallocate failed no space left on devide" and the experiment failed, i used 'df -h /home' to show the use%, and i saw there still has some avail space(7.8G). as the same time, the experiment created a file named example……, the file's size is 0,but 'du -sh example……' shows 15G