Swap on BTRFS

[Patrick O'Callaghan]

The swapon(8) man page says:

The  swap  file  implementation in the kernel expects to be able to write
   to the file directly, without the assistance of the filesystem.  This is a
   problem on files with holes or on copy-on-write files on filesystems like Btrfs.

As I'm getting OOM errors when I try to run a VM, it looks like I need
a swap file or partition. I'd prefer to use part of my (large) SSD for
this, but currently it's entirely formatted as BTRFS. Do I need to
resize the BTRFS partition rather than using a swap file?

poc