[proaralyst]

The trick was to insert a USB drive, tell BTRFS it's block storage and delete away. Once you're done you tell it not to use the disk and you're good.

This is why I'm back on ext4 now, too.

[zlynx]

I do a similar thing with my laptop's swap partition. swapoff, add it to btrfs, then remove it and mkswap again. Always seemed safer than a potentially dodgy USB drive.

[adamzegelin]

Or, if you don't care about your data, add a RAM disk :P

[tezzer]

Good trick, I'll save that one. Thanks!