kernel 4.7.4-100.fc23.x86_64 reports 512, thank you for fixing it: $ cat /sys/dev/block/8:0/queue/discard_granularity 512
kernel 4.7.4-100. fc23.x86_ 64 reports 512, thank you for fixing it: block/8: 0/queue/ discard_ granularity
$ cat /sys/dev/
512