On 2014-10-14 18:25, Robert White wrote:
> I've got no idea if this is possible given the current storage layout,
> but it would be Really Nice™ if there were a way to have a single
> subvolume exist in more than one place in hirearchy. I know this can be
> faked via mount tricks (bind or use of subvol=), but having it be a real
> thing would be preferable.
>
> For example, if I have two or more distributions on a computer or want
> to switch between 32bit and 64bit environments frequently, but I want to
> use the same /home (which is its own subvolume anyway) it would be nice
> if the native layout could be permuted such that /__System_32/home and
> /__System_64/home were the actual same subvolume.
>
> The mechanism, were it possible, would be something like "btrfs
> subvolume link /existing/path /new/path" (or "bind" instead of "link")
>
> I've got no idea if the directory structure would allow for this, but if
> it would it would simplify several things (for me anyway) if the file
> system layout represented the runtime layout.
This probably won't be implemented, for the same reason that most modern 
unix systems disallow hardlinks to directories; namely, it results in 
ambiguity regarding resolution of the .. directory entry.
The better solution would be to put /home in a separate top-level 
sub-volume, and then mount that in each location.