Expanding Ext4 Volume on ZFS

Due to Dropbox’s idiotic decision to limit file system support drastically for no reason other than to piss people off, I have a small ext4 volume hosted on my ZFS pool.

Originally I made it a bit small (only 8 GB) and got Dropbox complaining. Had I created it as partition, enlarging it would be annoying task at best. However, having it exposed as ZFS block volume, resize was trivial.

First I simply increased volsize property and then told ext4 to simply use that additional space (resize2fs command):

sudo zfs set volsize=^^16G^^ ^^rpool/data/dropbox^^

sudo resize2fs ^^/dev/zvol/rpool/data/dropbox^^
 resize2fs 1.44.4 (18-Aug-2018)
 Filesystem at /dev/zvol/rpool/data/dropbox is mounted on /home/user/Dropbox; on-line resizing required
 old_desc_blocks = 1, new_desc_blocks = 2
 The filesystem on /dev/zvol/rpool/data/dropbox is now 4194304 (4k) blocks long.

Doesn’t get much easier.