042dd4be1f
With the addition of the map/unmap_volume() methods we made an (actually unnecessary) API version bump. All current users of these methods fall back to path() when they return undef, so plugins implementing version 1 are in fact compatible currently. (In fact, the default Plugin::map_volume() could fall back to it on its own, but doesn't currently). For now let's just allow plugins older plugins to also be loaded by introducing an API age variable. With it, if we have a reason to break older plugins, we can have a deprecation period during which older plugins cause a warning instead of refusing to load altogether. Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>