[RFC PATCH 08/11] mm/damon/sysfs-schemes: implement scheme filters

[SeongJae Park <sj@xxxxxxxxxx>]

Implement scheme filters functionality of DAMON sysfs interface by
making the code reads the values of files under the filter directories
and pass that to DAMON using DAMON kernel API.

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 mm/damon/sysfs-schemes.c | 85 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 84 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 7f2bab617156..6f014b328e6f 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1402,6 +1402,71 @@ struct kobj_type damon_sysfs_schemes_ktype = {
 	.default_groups = damon_sysfs_schemes_groups,
 };
 
+static bool damon_sysfs_memcg_path_eq(struct mem_cgroup *memcg,
+		char *memcg_path_buf, char *path)
+{
+#ifdef CONFIG_CGROUPS
+	cgroup_path(memcg->css.cgroup, memcg_path_buf, PATH_MAX);
+	if (sysfs_streq(memcg_path_buf, path))
+		return true;
+#endif
+	return false;
+}
+
+static int damon_sysfs_memcg_path_to_id(char *memcg_path, unsigned short *id)
+{
+	struct mem_cgroup *memcg;
+	char *path;
+
+	if (!memcg_path)
+		return -EINVAL;
+
+	path = kmalloc(sizeof(*path) * PATH_MAX, GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	for (memcg = mem_cgroup_iter(NULL, NULL, NULL); memcg;
+			memcg = mem_cgroup_iter(NULL, memcg, NULL)) {
+		if (damon_sysfs_memcg_path_eq(memcg, path, memcg_path)) {
+			*id = mem_cgroup_id(memcg);
+			break;
+		}
+	}
+
+	kfree(path);
+	return 0;
+}
+
+static int damon_sysfs_set_scheme_filters(struct damos *scheme,
+		struct damon_sysfs_scheme_filters *sysfs_filters)
+{
+	int i;
+	struct damos_filter *filter, *next;
+
+	damos_for_each_filter_safe(filter, next, scheme)
+		damos_destroy_filter(filter);
+
+	for (i = 0; i < sysfs_filters->nr; i++) {
+		struct damon_sysfs_scheme_filter *sysfs_filter =
+			sysfs_filters->filters_arr[i];
+		struct damos_filter *filter =
+			damos_new_filter(sysfs_filter->type,
+					sysfs_filter->matching);
+		int err;
+
+		if (!filter)
+			return -ENOMEM;
+		if (filter->type == DAMOS_FILTER_TYPE_MEMCG) {
+			err = damon_sysfs_memcg_path_to_id(
+					sysfs_filter->memcg_path,
+					&filter->memcg_id);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
 static struct damos *damon_sysfs_mk_scheme(
 		struct damon_sysfs_scheme *sysfs_scheme)
 {
@@ -1410,6 +1475,10 @@ static struct damos *damon_sysfs_mk_scheme(
 	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
 	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
 	struct damon_sysfs_watermarks *sysfs_wmarks = sysfs_scheme->watermarks;
+	struct damon_sysfs_scheme_filters *sysfs_filters =
+		sysfs_scheme->filters;
+	struct damos *scheme;
+	int err;
 
 	struct damos_access_pattern pattern = {
 		.min_sz_region = access_pattern->sz->min,
@@ -1435,8 +1504,17 @@ static struct damos *damon_sysfs_mk_scheme(
 		.low = sysfs_wmarks->low,
 	};
 
-	return damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
+	scheme = damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
 			&wmarks);
+	if (!scheme)
+		return NULL;
+
+	err = damon_sysfs_set_scheme_filters(scheme, sysfs_filters);
+	if (err) {
+		damon_destroy_scheme(scheme);
+		return NULL;
+	}
+	return scheme;
 }
 
 static void damon_sysfs_update_scheme(struct damos *scheme,
@@ -1447,6 +1525,7 @@ static void damon_sysfs_update_scheme(struct damos *scheme,
 	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
 	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
 	struct damon_sysfs_watermarks *sysfs_wmarks = sysfs_scheme->watermarks;
+	int err;
 
 	scheme->pattern.min_sz_region = access_pattern->sz->min;
 	scheme->pattern.max_sz_region = access_pattern->sz->max;
@@ -1469,6 +1548,10 @@ static void damon_sysfs_update_scheme(struct damos *scheme,
 	scheme->wmarks.high = sysfs_wmarks->high;
 	scheme->wmarks.mid = sysfs_wmarks->mid;
 	scheme->wmarks.low = sysfs_wmarks->low;
+
+	err = damon_sysfs_set_scheme_filters(scheme, sysfs_scheme->filters);
+	if (err)
+		damon_destroy_scheme(scheme);
 }
 
 int damon_sysfs_set_schemes(struct damon_ctx *ctx,
-- 
2.25.1