[RFC PATCH 02/13] mm/damon/sysfs-schemes: support address range type DAMOS filter

[SeongJae Park <sj@kernel.org>]

Extend DAMON sysfs interface to support address range based DAMOS
filters, by adding a special keyword for the filter/<N>/type file,
namely 'addr', and two files under filter/<N>/ for specifying the start
and the end addresses of the range, namely 'addr_start' and 'addr_end'.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 56 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 9a015079f3a4..03ddba3e216d 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -282,6 +282,7 @@ struct damon_sysfs_scheme_filter {
 	enum damos_filter_type type;
 	bool matching;
 	char *memcg_path;
+	struct damon_addr_range addr_range;
 };
 
 static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(void)
@@ -293,6 +294,7 @@ static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(void)
 static const char * const damon_sysfs_scheme_filter_type_strs[] = {
 	"anon",
 	"memcg",
+	"addr",
 };
 
 static ssize_t type_show(struct kobject *kobj,
@@ -373,6 +375,44 @@ static ssize_t memcg_path_store(struct kobject *kobj,
 	return count;
 }
 
+static ssize_t addr_start_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	return sysfs_emit(buf, "%lu\n", filter->addr_range.start);
+}
+
+static ssize_t addr_start_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+	int err = kstrtoul(buf, 0, &filter->addr_range.start);
+
+	return err ? err : count;
+}
+
+static ssize_t addr_end_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	return sysfs_emit(buf, "%lu\n", filter->addr_range.end);
+}
+
+static ssize_t addr_end_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+	int err = kstrtoul(buf, 0, &filter->addr_range.end);
+
+	return err ? err : count;
+}
+
 static void damon_sysfs_scheme_filter_release(struct kobject *kobj)
 {
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
@@ -391,10 +431,18 @@ static struct kobj_attribute damon_sysfs_scheme_filter_matching_attr =
 static struct kobj_attribute damon_sysfs_scheme_filter_memcg_path_attr =
 		__ATTR_RW_MODE(memcg_path, 0600);
 
+static struct kobj_attribute damon_sysfs_scheme_filter_addr_start_attr =
+		__ATTR_RW_MODE(addr_start, 0600);
+
+static struct kobj_attribute damon_sysfs_scheme_filter_addr_end_attr =
+		__ATTR_RW_MODE(addr_end, 0600);
+
 static struct attribute *damon_sysfs_scheme_filter_attrs[] = {
 	&damon_sysfs_scheme_filter_type_attr.attr,
 	&damon_sysfs_scheme_filter_matching_attr.attr,
 	&damon_sysfs_scheme_filter_memcg_path_attr.attr,
+	&damon_sysfs_scheme_filter_addr_start_attr.attr,
+	&damon_sysfs_scheme_filter_addr_end_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_scheme_filter);
@@ -1484,7 +1532,15 @@ static int damon_sysfs_set_scheme_filters(struct damos *scheme,
 				damos_destroy_filter(filter);
 				return err;
 			}
+		} else if (filter->type == DAMOS_FILTER_TYPE_ADDR) {
+			if (sysfs_filter->addr_range.end <
+					sysfs_filter->addr_range.start) {
+				damos_destroy_filter(filter);
+				return -EINVAL;
+			}
+			filter->addr_range = sysfs_filter->addr_range;
 		}
+
 		damos_add_filter(scheme, filter);
 	}
 	return 0;
-- 
2.25.1