cgroup: add cgroup_subsys->css_e_css_changed()
Add a new cgroup_subsys operatoin ->css_e_css_changed(). This is
invoked if any of the effective csses seen from the css's cgroup may
have changed. This will be used to implement cgroup writeback
support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c855869..69f0335 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2836,6 +2836,24 @@
}
}
+ /*
+ * The effective csses of all the descendants (excluding @cgrp) may
+ * have changed. Subsystems can optionally subscribe to this event
+ * by implementing ->css_e_css_changed() which is invoked if any of
+ * the effective csses seen from the css's cgroup may have changed.
+ */
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss);
+ struct cgroup_subsys_state *css;
+
+ if (!ss->css_e_css_changed || !this_css)
+ continue;
+
+ css_for_each_descendant_pre(css, this_css)
+ if (css != this_css)
+ ss->css_e_css_changed(css);
+ }
+
kernfs_activate(cgrp->kn);
ret = 0;
out_unlock:
