DragonFlyBSD

I mount a HAMMER file system called /www
$df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/da0s1a 252M 88M 144M 38% /
/dev/da0s1d 252M 25M 207M 11% /var
/dev/da0s1e 252M 14K 232M 0% /tmp
/dev/da0s1f 7.9G 2.1G 5.1G 30% /usr
/dev/da0s1g 29G 169M 26G 1% /home
procfs 4.0K 4.0K 0B 100% /proc
www 19G 0M 19G 0% /www

I create a php file which content is

Then after days,run df -h again:
$df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/da0s1a 252M 88M 144M 38% /
/dev/da0s1d 252M 25M 207M 11% /var
/dev/da0s1e 252M 14K 232M 0% /tmp
/dev/da0s1f 7.9G 2.1G 5.1G 30% /usr
/dev/da0s1g 29G 169M 26G 1% /home
procfs 4.0K 4.0K 0B 100% /proc
www 19G 8.0M 19G 0% /www

I am not run a cron to reblock /www
which file(s) consume the 8m space?

Or run a cron like
15 2 * * * hammer -c /var/run/www -t 300 reblock /www >/dev/null 2>&1
would make it better?

$hammer -c /var/run/www -t 300 reblock /www
reblock free level 0
Reblock /www succeeded
Reblocked:
1/1 btree nodes
9/9 data elements
909/909 data bytes
$df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/da0s1a 252M 88M 144M 38% /
/dev/da0s1d 252M 25M 207M 11% /var
/dev/da0s1e 252M 14K 232M 0% /tmp
/dev/da0s1f 7.9G 2.1G 5.1G 30% /usr
/dev/da0s1g 29G 169M 26G 1% /home
procfs 4.0K 4.0K 0B 100% /proc
www 19G 8.0M 19G 0% /www

the 8M space is not released.