[linux-lvm] Reserve space for specific thin logical volumes

[matthew patton]

> Let me de-tour by using ZFS as an example

with the obvious caveat that in ZFS the block layer and the file layers are VERY tightly coupled. LVM and the block layer see eye-to-eye but ext4 et. al. have absolutely (almost?) no clue what's going on beneath it and thus LVM is making (false) guarantees that the filesystem is relying upon to actually be true.

IMO Thin-Pool is like waving around a lit welding torch - it's incredibly useful to do certain tasks but you can easily burn yourself and the building down if you don't handle it properly.