Add a variant of DAMOS_QUOTA_NODE_MEMCG_USED_BP, for free memory
portion.  Note that this commit only extends the DAMON API.  The real
behavior will be implemented by a following commit.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 43aef959d357..ba02c95e7d85 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -176,6 +176,7 @@ enum damos_action {
  * @DAMOS_QUOTA_NODE_MEM_USED_BP:	MemUsed ratio of a node.
  * @DAMOS_QUOTA_NODE_MEM_FREE_BP:	MemFree ratio of a node.
  * @DAMOS_QUOTA_NODE_MEMCG_USED_BP:	MemUsed ratio of a node for a cgroup.
+ * @DAMOS_QUOTA_NODE_MEMCG_FREE_BP:	MemFree ratio of a node for a cgroup.
  * @DAMOS_QUOTA_ACTIVE_MEM_BP:		Active to inactive memory ratio.
  * @NR_DAMOS_QUOTA_GOAL_METRICS:	Number of DAMOS quota goal metrics.
  *
@@ -187,6 +188,7 @@ enum damos_quota_goal_metric {
 	DAMOS_QUOTA_NODE_MEM_USED_BP,
 	DAMOS_QUOTA_NODE_MEM_FREE_BP,
 	DAMOS_QUOTA_NODE_MEMCG_USED_BP,
+	DAMOS_QUOTA_NODE_MEMCG_FREE_BP,
 	DAMOS_QUOTA_ACTIVE_MEM_BP,
 	NR_DAMOS_QUOTA_GOAL_METRICS,
 };
@@ -213,8 +215,8 @@ enum damos_quota_goal_metric {
  * If @metric is DAMOS_QUOTA_NODE_MEM_{USED,FREE}_BP, @nid represents the node
  * id of the target node to account the used/free memory.
  *
- * If @metric is DAMOS_QUOTA_NODE_MEMCG_USED_BP, @nid and @memcg_id represents
- * the node id and the cgroup to account the used memory for.
+ * If @metric is DAMOS_QUOTA_NODE_MEMCG_{USED,FREE}_BP, @nid and @memcg_id
+ * represents the node id and the cgroup to account the used memory for.
  */
 struct damos_quota_goal {
 	enum damos_quota_goal_metric metric;
-- 
2.39.5