1 files changed, 74 insertions, 0 deletions
diff --git a/include/linux/zswap.h b/include/linux/zswap.h
new file mode 100644
index 000000000000..30c193a1207e
--- /dev/null
+++ b/include/linux/zswap.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_ZSWAP_H
+#define _LINUX_ZSWAP_H
+
+#include <linux/types.h>
+#include <linux/mm_types.h>
+
+struct lruvec;
+
+extern atomic_long_t zswap_stored_pages;
+
+#ifdef CONFIG_ZSWAP
+
+struct zswap_lruvec_state {
+	/*
+	 * Number of swapped in pages from disk, i.e not found in the zswap pool.
+	 *
+	 * This is consumed and subtracted from the lru size in
+	 * zswap_shrinker_count() to penalize past overshrinking that led to disk
+	 * swapins. The idea is that had we considered this many more pages in the
+	 * LRU active/protected and not written them back, we would not have had to
+	 * swapped them in.
+	 */
+	atomic_long_t nr_disk_swapins;
+};
+
+unsigned long zswap_total_pages(void);
+bool zswap_store(struct folio *folio);
+int zswap_load(struct folio *folio);
+void zswap_invalidate(swp_entry_t swp);
+int zswap_swapon(int type, unsigned long nr_pages);
+void zswap_swapoff(int type);
+void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg);
+void zswap_lruvec_state_init(struct lruvec *lruvec);
+void zswap_folio_swapin(struct folio *folio);
+bool zswap_is_enabled(void);
+bool zswap_never_enabled(void);
+#else
+
+struct zswap_lruvec_state {};
+
+static inline bool zswap_store(struct folio *folio)
+{
+	return false;
+}
+
+static inline int zswap_load(struct folio *folio)
+{
+	return -ENOENT;
+}
+
+static inline void zswap_invalidate(swp_entry_t swp) {}
+static inline int zswap_swapon(int type, unsigned long nr_pages)
+{
+	return 0;
+}
+static inline void zswap_swapoff(int type) {}
+static inline void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg) {}
+static inline void zswap_lruvec_state_init(struct lruvec *lruvec) {}
+static inline void zswap_folio_swapin(struct folio *folio) {}
+
+static inline bool zswap_is_enabled(void)
+{
+	return false;
+}
+
+static inline bool zswap_never_enabled(void)
+{
+	return true;
+}
+
+#endif
+
+#endif /* _LINUX_ZSWAP_H */