One concern worth noting: this patch changes the format of vol->key for multipath volumes from a device path (/dev/mapper/mpathX) to a device-mapper UUID (e.g., mpath-3600508b4000c4a5d0000300000490000) when one is available.
This could affect API consumers or management tools (like oVirt or virt-manager) that store or compare volume keys and expect the previous path-based format. However, the old keys were already unreliable — device paths like /dev/mapper/mpath0 can change across reboots when devices enumerate in a different order, which is precisely the bug this patch addresses. Any consumer relying on the old key for stable identification was already broken in practice, they just hadn't noticed until a reboot shuffled the device order. The fallback to the device path when no UUID is available preserves the existing behavior for devices that lack a UUID.
