Is theire any specific caution to take before resize btrfs

### Current situation I have an almost full /home partition, with just 4.4Go remaining space, when my / is more than half empty. Both of the two partitions are in Btrfs, as you can see:

% lsblk -o NAME,FSTYPE,FSAVAIL,FSUSE%,MOUNTPOINT,SIZE -e7
NAME   FSTYPE FSAVAIL FSUSE% MOUNTPOINT              SIZE
sda                                                238,5G
├─sda1 vfat      4,6G     0% /boot/efi               4,7G
├─sda2 swap                  [SWAP]                  4,8G
├─sda3 btrfs    67,0G    37% / 107,1G              107,1G
└─sda4 btrfs     4,4G    96% /home                   122G

### What I want to do Then naturaly I want to downsise the / partition to make more space to /home. ### The question Before downsizing / and upsizing /home I am naturally afraid. I know their is no defragmentation tool for Btrfs because the specific mechanism of Btrfs have no need, but I still a little bit incredulous. At least, is their a defragmentation analizis tool for Btrfs or something allowing me to know how safe the resizing will be? Is their any caution I can take before? Naturally I made a backup before. But if I can avoid to restore them it would be great.