For some cgroup controllers, the behavior on cgroup v1 differs somewhat
from cgroup v2. To indicate that a controller can use v2 behavior
in cgroup v1, a new cgroupfs mount option "v2_mode" is added. This
is essentially a hint, there is no obligation for a controller to
comply with this semantics.
Signed-off-by: Waiman Long <long...@redhat.com>
---
include/linux/cgroup-defs.h | 5 +++++
kernel/cgroup/cgroup-v1.c | 6 ++++++
2 files changed, 11 insertions(+)
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 09f4c7d..fae33ed 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -74,6 +74,11 @@ enum {
* aren't writeable from inside the namespace.
*/
CGRP_ROOT_NS_DELEGATE = (1 << 3),
+
+ /*
+ * A hint that v1 cgroup should use v2 behavior, if applicable.
+ */
+ CGRP_ROOT_V2_MODE = (1 << 4),
};
/* cftype->flags */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 7bf4b15..77e22a4 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -846,6 +846,8 @@ static int cgroup1_show_options(struct seq_file *seq,
struct kernfs_root *kf_roo
seq_puts(seq, ",noprefix");
if (root->flags & CGRP_ROOT_XATTR)
seq_puts(seq, ",xattr");
+ if (root->flags & CGRP_ROOT_V2_MODE)
+ seq_puts(seq, ",v2_mode");
spin_lock(&release_agent_path_lock);
if (strlen(root->release_agent_path))
@@ -900,6 +902,10 @@ static int parse_cgroupfs_options(char *data, struct
cgroup_sb_opts *opts)
opts->cpuset_clone_children = true;
continue;
}
+ if (!strcmp(token, "v2_mode")) {
+ opts->flags |= CGRP_ROOT_V2_MODE;
+ continue;
+ }
if (!strcmp(token, "xattr")) {
opts->flags |= CGRP_ROOT_XATTR;
continue;
--
1.8.3.1
