[wishlist] BcacheFS as root filesystem

[BP25]

Hello, I sent this on help guix mailinglist but I now realise that it's 
more suitable for the devel mailing list because it's about a feature 
not yet implemented. I read on the manual the following: is it still 
current or are there workarounds for having BcacheFS as root FS? (let's 
forget for an instant about the recent additional complication of 
exclusion from mainline linux). Many thanks for your help!!

Currently Guix System only supports ext4, btrfs, JFS, F2FS, and XFS file 
systems. In particular, code that reads file system UUIDs and labels 
only works for these file system types.