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.

[akpm@linux-foundation.org: make damos_sysfs_action_names static]
  Closes: https://lore.kernel.org/oe-kbuild-all/202506271655.b8yfEZIT-lkp@intel.com/
Link: https://lkml.kernel.org/r/20250622213759.50930-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 3747dc6678f292a837529b722a2cc3f9ab98724b..8a00a76a713f5169079aee4083427efd10b289d4 100644 (file)
--- 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;
+};
+
+static 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;
                }
        }