[PATCH 02/12] mm/damon/sysfs-schemes: introduce nr_snapshots damos stat file

SeongJae Park
2025-12-16T08:01:45Z

Introduce a new DAMON sysfs interface file for exposing the newly added
DAMOS stat, nr_snapshots. The file has the name same to the stat name
(nr_snapshots) and placed under the damos stat sysfs directory.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/sysfs-schemes.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index a71059e65d34..a1f555e1125a 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -204,6 +204,7 @@ struct damon_sysfs_stats {
unsigned long sz_applied;
unsigned long sz_ops_filter_passed;
unsigned long qt_exceeds;
+ unsigned long nr_snapshots;
};

static struct damon_sysfs_stats *damon_sysfs_stats_alloc(void)
@@ -265,6 +266,15 @@ static ssize_t qt_exceeds_show(struct kobject *kobj,
return sysfs_emit(buf, "%lu\n", stats->qt_exceeds);
}

+static ssize_t nr_snapshots_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct damon_sysfs_stats *stats = container_of(kobj,
+ struct damon_sysfs_stats, kobj);
+
+ return sysfs_emit(buf, "%lu\n", stats->nr_snapshots);
+}
+
static void damon_sysfs_stats_release(struct kobject *kobj)
{
kfree(container_of(kobj, struct damon_sysfs_stats, kobj));
@@ -288,6 +298,9 @@ static struct kobj_attribute damon_sysfs_stats_sz_ops_filter_passed_attr =
static struct kobj_attribute damon_sysfs_stats_qt_exceeds_attr =
__ATTR_RO_MODE(qt_exceeds, 0400);

+static struct kobj_attribute damon_sysfs_stats_nr_snapshots_attr =
+ __ATTR_RO_MODE(nr_snapshots, 0400);
+
static struct attribute *damon_sysfs_stats_attrs[] = {
&damon_sysfs_stats_nr_tried_attr.attr,
&damon_sysfs_stats_sz_tried_attr.attr,
@@ -295,6 +308,7 @@ static struct attribute *damon_sysfs_stats_attrs[] = {
&damon_sysfs_stats_sz_applied_attr.attr,
&damon_sysfs_stats_sz_ops_filter_passed_attr.attr,
&damon_sysfs_stats_qt_exceeds_attr.attr,
+ &damon_sysfs_stats_nr_snapshots_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_stats);
@@ -2760,6 +2774,7 @@ void damon_sysfs_schemes_update_stats(
sysfs_stats->sz_ops_filter_passed =
scheme->stat.sz_ops_filter_passed;
sysfs_stats->qt_exceeds = scheme->stat.qt_exceeds;
+ sysfs_stats->nr_snapshots = scheme->stat.nr_snapshots;
}
}

--
2.47.3