linux-kernel - [PATCH 2/5] mm/damon/sysfs-schemes: decouple from damos

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Message-Id: <20250622213759.50930-3-sj@kernel.org>
Date: Sun, 22 Jun 2025 14:37:56 -0700
From: SeongJae Park <sj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: SeongJae Park <sj@...nel.org>,
	damon@...ts.linux.dev,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH 2/5] mm/damon/sysfs-schemes: decouple from damos_action

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

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/sysfs-schemes.c | 80 +++++++++++++++++++++++++++++++---------
 1 file changed, 62 insertions(+), 18 deletions(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 3747dc6678f2..117d27544173 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1614,18 +1614,52 @@ struct damon_sysfs_scheme {
 	int target_nid;
 };
 
-/* This should match with enum damos_action */
-static const char * const damon_sysfs_damos_action_strs[] = {
-	"willneed",
-	"cold",
-	"pageout",
-	"hugepage",
-	"nohugepage",
-	"lru_prio",
-	"lru_deprio",
-	"migrate_hot",
-	"migrate_cold",
-	"stat",
+struct damos_sysfs_action_name {
+	enum damos_action action;
+	char *name;
+};
+
+struct damos_sysfs_action_name damos_sysfs_action_names[] = {
+	{
+		.action = DAMOS_WILLNEED,
+		.name = "willneed",
+	},
+	{
+		.action = DAMOS_COLD,
+		.name = "cold",
+	},
+	{
+		.action = DAMOS_PAGEOUT,
+		.name = "pageout",
+	},
+	{
+		.action = DAMOS_HUGEPAGE,
+		.name = "hugepage",
+	},
+	{
+		.action = DAMOS_NOHUGEPAGE,
+		.name = "nohugepage",
+	},
+	{
+		.action = DAMOS_LRU_PRIO,
+		.name = "lru_prio",
+	},
+	{
+		.action = DAMOS_LRU_DEPRIO,
+		.name = "lru_deprio",
+	},
+	{
+		.action = DAMOS_MIGRATE_HOT,
+		.name = "migrate_hot",
+	},
+	{
+		.action = DAMOS_MIGRATE_COLD,
+		.name = "migrate_cold",
+	},
+	{
+		.action = DAMOS_STAT,
+		.name = "stat",
+	},
 };
 
 static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc(
@@ -1862,9 +1896,16 @@ static ssize_t action_show(struct kobject *kobj, struct kobj_attribute *attr,
 {
 	struct damon_sysfs_scheme *scheme = container_of(kobj,
 			struct damon_sysfs_scheme, kobj);
+	int i;
 
-	return sysfs_emit(buf, "%s\n",
-			damon_sysfs_damos_action_strs[scheme->action]);
+	for (i = 0; i < ARRAY_SIZE(damos_sysfs_action_names); i++) {
+		struct damos_sysfs_action_name *action_name;
+
+		action_name = &damos_sysfs_action_names[i];
+		if (action_name->action == scheme->action)
+			return sysfs_emit(buf, "%s\n", action_name->name);
+	}
+	return -EINVAL;
 }
 
 static ssize_t action_store(struct kobject *kobj, struct kobj_attribute *attr,
@@ -1872,11 +1913,14 @@ static ssize_t action_store(struct kobject *kobj, struct kobj_attribute *attr,
 {
 	struct damon_sysfs_scheme *scheme = container_of(kobj,
 			struct damon_sysfs_scheme, kobj);
-	enum damos_action action;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damos_sysfs_action_names); i++) {
+		struct damos_sysfs_action_name *action_name;
 
-	for (action = 0; action < NR_DAMOS_ACTIONS; action++) {
-		if (sysfs_streq(buf, damon_sysfs_damos_action_strs[action])) {
-			scheme->action = action;
+		action_name = &damos_sysfs_action_names[i];
+		if (sysfs_streq(buf, action_name->name)) {
+			scheme->action = action_name->action;
 			return count;
 		}
 	}
-- 
2.39.5