[PATCH v3 2/4] Enable balloon drivers to report inflated memory

[Alexander Atanasov <alexander.atanasov@virtuozzo.com>]

Add counters to be updated by the balloon drivers.
Create balloon notifier to propagate changes.

Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
---
 include/linux/balloon.h | 18 ++++++++++++++++++
 mm/balloon.c            | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/include/linux/balloon.h b/include/linux/balloon.h
index 46ac8f61f607..59657da77d95 100644
--- a/include/linux/balloon.h
+++ b/include/linux/balloon.h
@@ -57,6 +57,24 @@ struct balloon_dev_info {
 			struct page *page, enum migrate_mode mode);
 };
 
+extern atomic_long_t mem_balloon_inflated_total_kb;
+extern atomic_long_t mem_balloon_inflated_free_kb;
+
+void balloon_set_inflated_total(long inflated_kb);
+void balloon_set_inflated_free(long inflated_kb);
+
+#define BALLOON_CHANGED_TOTAL 0
+#define BALLOON_CHANGED_FREE  1
+
+int register_balloon_notifier(struct notifier_block *nb);
+void unregister_balloon_notifier(struct notifier_block *nb);
+
+#define balloon_notifier(fn, pri) ({						\
+	static struct notifier_block fn##_mem_nb __meminitdata =\
+		{ .notifier_call = fn, .priority = pri };			\
+	register_balloon_notifier(&fn##_mem_nb);				\
+})
+
 struct page *balloon_page_alloc(void);
 void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
 				 struct page *page);
diff --git a/mm/balloon.c b/mm/balloon.c
index 22b3e876bc78..8e1d5855fef8 100644
--- a/mm/balloon.c
+++ b/mm/balloon.c
@@ -7,8 +7,44 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/notifier.h>
 #include <linux/balloon.h>
 
+atomic_long_t mem_balloon_inflated_total_kb = ATOMIC_LONG_INIT(0);
+atomic_long_t mem_balloon_inflated_free_kb = ATOMIC_LONG_INIT(0);
+SRCU_NOTIFIER_HEAD_STATIC(balloon_chain);
+
+int register_balloon_notifier(struct notifier_block *nb)
+{
+	return srcu_notifier_chain_register(&balloon_chain, nb);
+}
+EXPORT_SYMBOL(register_balloon_notifier);
+
+void unregister_balloon_notifier(struct notifier_block *nb)
+{
+	srcu_notifier_chain_unregister(&balloon_chain, nb);
+}
+EXPORT_SYMBOL(unregister_balloon_notifier);
+
+static int balloon_notify(unsigned long val)
+{
+	return srcu_notifier_call_chain(&balloon_chain, val, NULL);
+}
+
+void balloon_set_inflated_total(long inflated_kb)
+{
+	atomic_long_set(&mem_balloon_inflated_total_kb, inflated_kb);
+	balloon_notify(BALLOON_CHANGED_TOTAL);
+}
+EXPORT_SYMBOL(balloon_set_inflated_total);
+
+void balloon_set_inflated_free(long inflated_kb)
+{
+	atomic_long_set(&mem_balloon_inflated_free_kb, inflated_kb);
+	balloon_notify(BALLOON_CHANGED_FREE);
+}
+EXPORT_SYMBOL(balloon_set_inflated_free);
+
 static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
 				     struct page *page)
 {
-- 
2.31.1