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

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 75 ++++++++++++++++++++++++++++++----------
 1 file changed, 57 insertions(+), 18 deletions(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 3d42d24bb33a..5243b94cec24 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -341,16 +341,45 @@ static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(
 	return filter;
 }
 
-/* Should match with enum damos_filter_type */
-static const char * const damon_sysfs_scheme_filter_type_strs[] = {
-	"anon",
-	"active",
-	"memcg",
-	"young",
-	"hugepage_size",
-	"unmapped",
-	"addr",
-	"target",
+struct damos_sysfs_filter_type_name {
+	enum damos_filter_type type;
+	char *name;
+};
+
+static const struct damos_sysfs_filter_type_name
+damos_sysfs_filter_type_names[] = {
+	{
+		.type = DAMOS_FILTER_TYPE_ANON,
+		.name = "anon",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_ACTIVE,
+		.name = "active",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_MEMCG,
+		.name = "memcg",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_YOUNG,
+		.name = "young",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_HUGEPAGE_SIZE,
+		.name = "hugepage_size",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_UNMAPPED,
+		.name = "unmapped",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_ADDR,
+		.name = "addr",
+	},
+	{
+		.type = DAMOS_FILTER_TYPE_TARGET,
+		.name = "target",
+	},
 };
 
 static ssize_t type_show(struct kobject *kobj,
@@ -358,9 +387,16 @@ static ssize_t type_show(struct kobject *kobj,
 {
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
 			struct damon_sysfs_scheme_filter, kobj);
+	int i;
 
-	return sysfs_emit(buf, "%s\n",
-			damon_sysfs_scheme_filter_type_strs[filter->type]);
+	for (i = 0; i < ARRAY_SIZE(damos_sysfs_filter_type_names); i++) {
+		const struct damos_sysfs_filter_type_name *type_name;
+
+		type_name = &damos_sysfs_filter_type_names[i];
+		if (type_name->type == filter->type)
+			return sysfs_emit(buf, "%s\n", type_name->name);
+	}
+	return -EINVAL;
 }
 
 static bool damos_sysfs_scheme_filter_valid_type(
@@ -385,16 +421,19 @@ static ssize_t type_store(struct kobject *kobj,
 {
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
 			struct damon_sysfs_scheme_filter, kobj);
-	enum damos_filter_type type;
 	ssize_t ret = -EINVAL;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damos_sysfs_filter_type_names); i++) {
+		const struct damos_sysfs_filter_type_name *type_name;
 
-	for (type = 0; type < NR_DAMOS_FILTER_TYPES; type++) {
-		if (sysfs_streq(buf, damon_sysfs_scheme_filter_type_strs[
-					type])) {
+		type_name = &damos_sysfs_filter_type_names[i];
+		if (sysfs_streq(buf, type_name->name)) {
 			if (!damos_sysfs_scheme_filter_valid_type(
-						filter->handle_layer, type))
+						filter->handle_layer,
+						type_name->type))
 				break;
-			filter->type = type;
+			filter->type = type_name->type;
 			ret = count;
 			break;
 		}
-- 
2.39.5