Hi! I’m learning how to use btrfs and I need some advice.

One one of my desktop, I made the mistake of creating 2 partitions, one for /(root) and one for home. Both are btrfs. I didn’t know that I could use subvolumes so that they could share the same physical space.

My question: How can I merge the root and home btrfs partitions into only 1 partition that would use btrfs subvolumes?

I’m looking for something like that:

• Partition1 (btrfs)
  • subvolume 1: @root (mounted to /)
  • subvolume 2: @home (mounted to /home)
• Partition 2, 3, 4…

My current setup:

• 1 physical hard drive (1 TB), shown as sda below
• The partitions I want to merge are sda7 and sda8
• That computer is an iMac also running MacOS so it has a few other partitions that I should not touch

$ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda      8:0    0 931,5G  0 disk 
├─sda1   8:1    0   200M  0 part /boot/efi
├─sda2   8:2    0 371,1G  0 part 
├─sda3   8:3    0 619,9M  0 part 
├─sda4   8:4    0   600M  0 part 
├─sda5   8:5    0  1023M  0 part 
├─sda7   8:7    0 422,9G  0 part /home
└─sda8   8:8    0 135,1G  0 part /
sdb      8:16   1     0B  0 disk 
sr0     11:0    1  1024M  0 rom  

$ blkid
/dev/sda4: UUID="d970eea2-142b-3f1c-9650-5e496d1e9b4b" BLOCK_SIZE="4096" LABEL="Linux HFS+ ESP" TYPE="hfsplus" PARTLABEL="Linux HFS+ ESP" PARTUUID="eab00592-b96d-4ecb-b2e9-816c95eaf860"
/dev/sda2: UUID="6a26963c-eabb-3e42-9e8d-8677a8282b61" BLOCK_SIZE="4096" LABEL="DD Macintosh" TYPE="hfsplus" PARTLABEL="DD Mac" PARTUUID="8257316c-1fd7-4885-bf2b-7e99557acd85"
/dev/sda7: UUID="22f5e59e-8509-484a-92d5-e7dc03bb70cd" UUID_SUB="78a998f5-db55-4a31-9506-afe548ec8d5e" BLOCK_SIZE="4096" TYPE="btrfs" PARTLABEL="Mint Home" PARTUUID="20b6c31d-5e2d-416f-beb3-faa295af67df"
/dev/sda5: UUID="587b0093-4b64-468a-9a01-b933630d184b" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="a47a3fbf-534a-435d-8916-0f83edebf296"
/dev/sda3: UUID="d0c171e8-572d-39f9-8bdc-38f33744a19a" BLOCK_SIZE="4096" LABEL="Recovery HD" TYPE="hfsplus" PARTLABEL="Recovery HD" PARTUUID="c9d0673b-bb2e-4322-9bf9-c661f7de6856"
/dev/sda1: LABEL_FATBOOT="EFI" LABEL="EFI" UUID="67E3-17ED" BLOCK_SIZE="512" TYPE="vfat" PARTLABEL="EFI System Partition" PARTUUID="d30954cb-b9b6-40fa-9202-a18cf146f7df"
/dev/sda8: UUID="7027382a-4369-4276-b916-9997c1007e5b" UUID_SUB="3e516464-dee1-4bda-9621-29591d54dc2d" BLOCK_SIZE="4096" TYPE="btrfs" PARTLABEL="Mint root" PARTUUID="f2fdb8cc-54fd-46c8-bf1f-85954c1dc363"