Based on https://rootlesscontaine.rs/getting-started/common/cgroup2/#enabling-cpu-cpuset-and-io-delegation , this patch enables I/O delegation for cgroups v2 enabled users. * gnu/services/containers.scm (cgroups-limits-entrypoint): Enable I/O controller delegation. * gnu/tests/containers.scm: Test it. Change-Id: I7caba33695f11830bea477c4ab3afb89cfaa2fa5 Signed-off-by: Ludovic Courtès <ludo@gnu.org>