#!/bin/bash

D=/dev/sda5
M=/mnt/btrfs

umount $M $D
mkfs.btrfs $D

mount $D $M -o autodefrag

fio fio_sync_random_write_4k_config &

for ((i=0; i<20; i++))
do
	btrfs sub snap $M $M/s_$i
	sleep 2
done &