busybox-1.26-x Using the f_frsize variable replacement the f_bsize variable.
I used one uClibc versions were seen to lose f_frsize(kernel return it, but then uClibc does not copy it). the f_frsize variable is 0 for the first time, and then it was not. The reason is that there is no initialization of the structure "struct 
 statfs s " in while(1).that's why it's wrong.

solution:
1. add  " #include <string.h> "
2. add  " memset(&s, 0, sizeof(struct statfs)); "  in while(1)