1 files changed, 76 insertions, 11 deletions

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 0f80123650e2..1a00be90d93a 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -2,9 +2,31 @@
 #ifndef _LINUX_SHRINKER_H
 #define _LINUX_SHRINKER_H
 
+#include <linux/atomic.h>
+#include <linux/types.h>
+#include <linux/refcount.h>
+#include <linux/completion.h>
+
+#define SHRINKER_UNIT_BITS	BITS_PER_LONG
+
+/*
+ * Bitmap and deferred work of shrinker::id corresponding to memcg-aware
+ * shrinkers, which have elements charged to the memcg.
+ */
+struct shrinker_info_unit {
+	atomic_long_t nr_deferred[SHRINKER_UNIT_BITS];
+	DECLARE_BITMAP(map, SHRINKER_UNIT_BITS);
+};
+
+struct shrinker_info {
+	struct rcu_head rcu;
+	int map_nr_max;
+	struct shrinker_info_unit *unit[];
+};
+
 /*
  * This struct is used to pass information from page reclaim to the shrinkers.
- * We consolidate the values for easier extention later.
+ * We consolidate the values for easier extension later.
  *
  * The 'gfpmask' refers to the allocation we are currently trying to
  * fulfil.
@@ -67,29 +89,72 @@ struct shrinker {
 	int seeks;	/* seeks to recreate an obj */
 	unsigned flags;
 
+	/*
+	 * The reference count of this shrinker. Registered shrinker have an
+	 * initial refcount of 1, then the lookup operations are now allowed
+	 * to use it via shrinker_try_get(). Later in the unregistration step,
+	 * the initial refcount will be discarded, and will free the shrinker
+	 * asynchronously via RCU after its refcount reaches 0.
+	 */
+	refcount_t refcount;
+	struct completion done;	/* use to wait for refcount to reach 0 */
+	struct rcu_head rcu;
+
+	void *private_data;
+
 	/* These are for internal use */
 	struct list_head list;
 #ifdef CONFIG_MEMCG
 	/* ID in shrinker_idr */
 	int id;
 #endif
+#ifdef CONFIG_SHRINKER_DEBUG
+	int debugfs_id;
+	const char *name;
+	struct dentry *debugfs_entry;
+#endif
 	/* objs pending delete, per node */
 	atomic_long_t *nr_deferred;
 };
 #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
 
-/* Flags */
-#define SHRINKER_NUMA_AWARE	(1 << 0)
-#define SHRINKER_MEMCG_AWARE	(1 << 1)
+/* Internal flags */
+#define SHRINKER_REGISTERED	BIT(0)
+#define SHRINKER_ALLOCATED	BIT(1)
+
+/* Flags for users to use */
+#define SHRINKER_NUMA_AWARE	BIT(2)
+#define SHRINKER_MEMCG_AWARE	BIT(3)
 /*
  * It just makes sense when the shrinker is also MEMCG_AWARE for now,
  * non-MEMCG_AWARE shrinker should not have this flag set.
  */
-#define SHRINKER_NONSLAB	(1 << 2)
+#define SHRINKER_NONSLAB	BIT(4)
 
-extern int prealloc_shrinker(struct shrinker *shrinker);
-extern void register_shrinker_prepared(struct shrinker *shrinker);
-extern int register_shrinker(struct shrinker *shrinker);
-extern void unregister_shrinker(struct shrinker *shrinker);
-extern void free_prealloced_shrinker(struct shrinker *shrinker);
-#endif
+__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);
+
+static inline bool shrinker_try_get(struct shrinker *shrinker)
+{
+	return refcount_inc_not_zero(&shrinker->refcount);
+}
+
+static inline void shrinker_put(struct shrinker *shrinker)
+{
+	if (refcount_dec_and_test(&shrinker->refcount))
+		complete(&shrinker->done);
+}
+
+#ifdef CONFIG_SHRINKER_DEBUG
+extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker,
+						  const char *fmt, ...);
+#else /* CONFIG_SHRINKER_DEBUG */
+static inline __printf(2, 3)
+int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
+{
+	return 0;
+}
+#endif /* CONFIG_SHRINKER_DEBUG */
+#endif /* _LINUX_SHRINKER_H */