mm/damon/sysfs-schemes: introduce nr_snapshots damos stat file

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.

Link: https://lkml.kernel.org/r/20251216080128.42991-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index b52fc3b45b309815747a9672306168d9729f5559..b7fcd7590ab38c143377f8ab4d853eb413d66191 100644 (file)
--- 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);
@@ -2762,6 +2776,7 @@ 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;
        }
 }