mm/damon/sysfs-schemes: decouple from damos_quota_goal_metric

Patch series "mm/damon: decouple sysfs from core".

DAMON sysfs interface is coupled with core layer.  It maintains some of
its keywords arrays be synchronized with matching DAMON core API enums. 
It is unnecessary coupling that makes separated changes for different
layers difficult.  Decouple the layers by introducing new data structure
for the mappings on DAMON sysfs interface.


This patch (of 5):

Decouple DAMOS sysfs interface from damos_quota_goal_metric.  For this,
define and use new sysfs-schemes internal data structure that maps the
user-space keywords and damos_quota_goal_metric, instead of having the
implicit and unflexible array index rule.

Link: https://lkml.kernel.org/r/20250622213759.50930-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250622213759.50930-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 41 insertions, 14 deletions

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 30ae7518ffbf..3747dc6678f2 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -941,27 +941,51 @@ struct damos_sysfs_quota_goal {
 	int nid;
 };
 
-/* This should match with enum damos_quota_goal_metric */
-static const char * const damos_sysfs_quota_goal_metric_strs[] = {
-	"user_input",
-	"some_mem_psi_us",
-	"node_mem_used_bp",
-	"node_mem_free_bp",
-};
-
 static struct damos_sysfs_quota_goal *damos_sysfs_quota_goal_alloc(void)
 {
 	return kzalloc(sizeof(struct damos_sysfs_quota_goal), GFP_KERNEL);
 }
 
+struct damos_sysfs_qgoal_metric_name {
+	enum damos_quota_goal_metric metric;
+	char *name;
+};
+
+static
+struct damos_sysfs_qgoal_metric_name damos_sysfs_qgoal_metric_names[] = {
+	{
+		.metric = DAMOS_QUOTA_USER_INPUT,
+		.name = "user_input",
+	},
+	{
+		.metric = DAMOS_QUOTA_SOME_MEM_PSI_US,
+		.name = "some_mem_psi_us",
+	},
+	{
+		.metric = DAMOS_QUOTA_NODE_MEM_USED_BP,
+		.name = "node_mem_used_bp",
+	},
+	{
+		.metric = DAMOS_QUOTA_NODE_MEM_FREE_BP,
+		.name = "node_mem_free_bp",
+	},
+};
+
 static ssize_t target_metric_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);
+	int i;
 
-	return sysfs_emit(buf, "%s\n",
-			damos_sysfs_quota_goal_metric_strs[goal->metric]);
+	for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_metric_names); i++) {
+		struct damos_sysfs_qgoal_metric_name *metric_name;
+
+		metric_name = &damos_sysfs_qgoal_metric_names[i];
+		if (metric_name->metric == goal->metric)
+			return sysfs_emit(buf, "%s\n", metric_name->name);
+	}
+	return -EINVAL;
 }
 
 static ssize_t target_metric_store(struct kobject *kobj,
@@ -969,11 +993,14 @@ static ssize_t target_metric_store(struct kobject *kobj,
 {
 	struct damos_sysfs_quota_goal *goal = container_of(kobj,
 			struct damos_sysfs_quota_goal, kobj);
-	enum damos_quota_goal_metric m;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_metric_names); i++) {
+		struct damos_sysfs_qgoal_metric_name *metric_name;
 
-	for (m = 0; m < NR_DAMOS_QUOTA_GOAL_METRICS; m++) {
-		if (sysfs_streq(buf, damos_sysfs_quota_goal_metric_strs[m])) {
-			goal->metric = m;
+		metric_name = &damos_sysfs_qgoal_metric_names[i];
+		if (sysfs_streq(buf, metric_name->name)) {
+			goal->metric = metric_name->metric;
 			return count;
 		}
 	}