mm/damon/sysfs-schemes: implement file for quota goal nid parameter

DAMOS_QUOTA_NODE_MEM_{USED,FREE}_BP DAMOS quota goal metrics require the
node id parameter.  However, there is no DAMON user ABI for setting it.
Implement a DAMON sysfs file for that with name 'nid', under the quota
goal directory.

Link: https://lkml.kernel.org/r/20250420194030.75838-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 98108f08217826dd75294961bc77db74d02164c9..7681ed293b626bb27dbd08abfe9fc04d825ad9e0 100644 (file)
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -936,6 +936,7 @@ struct damos_sysfs_quota_goal {
        enum damos_quota_goal_metric metric;
        unsigned long target_value;
        unsigned long current_value;
+       int nid;
 };
 
 /* This should match with enum damos_action */
@@ -1016,6 +1017,28 @@ static ssize_t current_value_store(struct kobject *kobj,
        return err ? err : count;
 }
 
+static ssize_t nid_show(struct kobject *kobj,
+               struct kobj_attribute *attr, char *buf)
+{
+       struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
+                       damos_sysfs_quota_goal, kobj);
+
+       /* todo: return error if the goal is not using nid */
+
+       return sysfs_emit(buf, "%d\n", goal->nid);
+}
+
+static ssize_t nid_store(struct kobject *kobj,
+               struct kobj_attribute *attr, const char *buf, size_t count)
+{
+       struct damos_sysfs_quota_goal *goal = container_of(kobj, struct
+                       damos_sysfs_quota_goal, kobj);
+       int err = kstrtoint(buf, 0, &goal->nid);
+
+       /* feed callback should check existence of this file and read value */
+       return err ? err : count;
+}
+
 static void damos_sysfs_quota_goal_release(struct kobject *kobj)
 {
        /* or, notify this release to the feed callback */
@@ -1031,10 +1054,14 @@ static struct kobj_attribute damos_sysfs_quota_goal_target_value_attr =
 static struct kobj_attribute damos_sysfs_quota_goal_current_value_attr =
                __ATTR_RW_MODE(current_value, 0600);
 
+static struct kobj_attribute damos_sysfs_quota_goal_nid_attr =
+               __ATTR_RW_MODE(nid, 0600);
+
 static struct attribute *damos_sysfs_quota_goal_attrs[] = {
        &damos_sysfs_quota_goal_target_metric_attr.attr,
        &damos_sysfs_quota_goal_target_value_attr.attr,
        &damos_sysfs_quota_goal_current_value_attr.attr,
+       &damos_sysfs_quota_goal_nid_attr.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(damos_sysfs_quota_goal);