[Linux] 磁盘空间被谁给占用了

/dev/sda2 为根分区，从 df 可以看到占用了 110G 空间，根分区下每个目录的空间和才 25G 左右，相差很大，问题出在哪里？环境：Fedora 36 Server 版，文件系统为 Btrfs 。

$ df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs 3.9G 376K 3.8G 1% /dev/shm
tmpfs 1.6G 1.6M 1.6G 1% /run
/dev/sda2 182G 110G 69G 62% /
tmpfs 3.9G 140K 3.9G 1% /tmp
/dev/sda1 5.0G 6.2M 5.0G 1% /boot/efi
tmpfs 779M 0 779M 0% /run/user/0
$ du -sh /*
0 /afs
4.0K /bin
269M /boot
16K /db
376K /dev
27M /etc
60K /home
4.0K /lib
4.0K /lib64
0 /media
8.0K /opt
0 /proc
4.3G /root
1.6M /run
4.0K /sbin
0 /srv
0 /sys
140K /tmp
3.7G /usr
16G /var

$ btrfs filesystem usage /
Overall:
Device size: 181.31GiB
Device allocated: 117.02GiB
Device unallocated: 64.29GiB
Device missing: 0.00B
Used: 109.80GiB
Free (estimated): 68.47GiB (min: 36.33GiB)
Free (statfs, df): 68.47GiB
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 166.55MiB (used: 0.00B)
Multiple profiles: no