mm/damon/sysfs: split out kdamond-independent schemes stats update logic into a new function

'damon_sysfs_schemes_update_stats()' is coupled with both
damon_sysfs_kdamond and damon_sysfs_schemes.  It's a wide range of types
dependency.  It makes splitting the logics a little bit distracting. 
Split the function so that each function is coupled with smaller range of
types.

Link: https://lkml.kernel.org/r/20221026225943.100429-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/sysfs.c

@@ -2246,25 +2246,13 @@ static void damon_sysfs_before_terminate(struct damon_ctx *ctx)
 	mutex_unlock(&ctx->kdamond_lock);
 }
 
-/*
- * damon_sysfs_upd_schemes_stats() - Update schemes stats sysfs files.
- * @kdamond:	The kobject wrapper that associated to the kdamond thread.
- *
- * This function reads the schemes stats of specific kdamond and update the
- * related values for sysfs files.  This function should be called from DAMON
- * callbacks while holding ``damon_syfs_lock``, to safely access the DAMON
- * contexts-internal data and DAMON sysfs variables.
- */
-static int damon_sysfs_upd_schemes_stats(struct damon_sysfs_kdamond *kdamond)
+static void damon_sysfs_schemes_update_stats(
+		struct damon_sysfs_schemes *sysfs_schemes,
+		struct damon_ctx *ctx)
 {
-	struct damon_ctx *ctx = kdamond->damon_ctx;
-	struct damon_sysfs_schemes *sysfs_schemes;
 	struct damos *scheme;
 	int schemes_idx = 0;
 
-	if (!ctx)
-		return -EINVAL;
-	sysfs_schemes = kdamond->contexts->contexts_arr[0]->schemes;
 	damon_for_each_scheme(scheme, ctx) {
 		struct damon_sysfs_stats *sysfs_stats;
 
@@ -2279,6 +2267,25 @@ static int damon_sysfs_upd_schemes_stats(struct damon_sysfs_kdamond *kdamond)
 		sysfs_stats->sz_applied = scheme->stat.sz_applied;
 		sysfs_stats->qt_exceeds = scheme->stat.qt_exceeds;
 	}
+}
+
+/*
+ * damon_sysfs_upd_schemes_stats() - Update schemes stats sysfs files.
+ * @kdamond:	The kobject wrapper that associated to the kdamond thread.
+ *
+ * This function reads the schemes stats of specific kdamond and update the
+ * related values for sysfs files.  This function should be called from DAMON
+ * callbacks while holding ``damon_syfs_lock``, to safely access the DAMON
+ * contexts-internal data and DAMON sysfs variables.
+ */
+static int damon_sysfs_upd_schemes_stats(struct damon_sysfs_kdamond *kdamond)
+{
+	struct damon_ctx *ctx = kdamond->damon_ctx;
+
+	if (!ctx)
+		return -EINVAL;
+	damon_sysfs_schemes_update_stats(
+			kdamond->contexts->contexts_arr[0]->schemes, ctx);
 	return 0;
 }