cgroup prefix option

cgroup-prefix.patch

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5ed7fc3..c1cc306 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1658,6 +1658,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
                        opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
                        continue;
                }
+               if (!strcmp(token, "prefix")) {
+                       opts->flags &= ~CGRP_ROOT_NOPREFIX;
+                       continue;
+               }
                if (!strcmp(token, "noprefix")) {
                        opts->flags |= CGRP_ROOT_NOPREFIX;
                        continue;