[PATCH 5/7] mm: shrinker: Add shrinker_to_text() to debugfs interface

[Kent Overstreet <kent.overstreet@linux.dev>]

Previously, we added shrinker_to_text() and hooked it up to the OOM
report - now, the same report is available via debugfs.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 include/linux/shrinker.h |  1 +
 mm/shrinker_debug.c      | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 497a7e8e348c..b8e57afabbcc 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -143,6 +143,7 @@ __printf(2, 3)
 struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...);
 void shrinker_register(struct shrinker *shrinker);
 void shrinker_free(struct shrinker *shrinker);
+void shrinker_to_text(struct seq_buf *, struct shrinker *);
 void shrinkers_to_text(struct seq_buf *);
 
 static inline bool shrinker_try_get(struct shrinker *shrinker)
diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
index 12ea5486a3e9..39342aa9f4ca 100644
--- a/mm/shrinker_debug.c
+++ b/mm/shrinker_debug.c
@@ -2,6 +2,7 @@
 #include <linux/idr.h>
 #include <linux/slab.h>
 #include <linux/debugfs.h>
+#include <linux/seq_buf.h>
 #include <linux/seq_file.h>
 #include <linux/shrinker.h>
 #include <linux/memcontrol.h>
@@ -159,6 +160,21 @@ static const struct file_operations shrinker_debugfs_scan_fops = {
 	.write	 = shrinker_debugfs_scan_write,
 };
 
+static int shrinker_debugfs_report_show(struct seq_file *m, void *v)
+{
+	struct shrinker *shrinker = m->private;
+	char *bufp;
+	size_t buflen = seq_get_buf(m, &bufp);
+	struct seq_buf out;
+
+	seq_buf_init(&out, bufp, buflen);
+	shrinker_to_text(&out, shrinker);
+	seq_commit(m, seq_buf_used(&out));
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_report);
+
 int shrinker_debugfs_add(struct shrinker *shrinker)
 {
 	struct dentry *entry;
@@ -190,6 +206,8 @@ int shrinker_debugfs_add(struct shrinker *shrinker)
 			    &shrinker_debugfs_count_fops);
 	debugfs_create_file("scan", 0220, entry, shrinker,
 			    &shrinker_debugfs_scan_fops);
+	debugfs_create_file("report", 0440, entry, shrinker,
+			    &shrinker_debugfs_report_fops);
 	return 0;
 }
 
-- 
2.42.0