1 files changed, 127 insertions, 0 deletions

diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h
new file mode 100644
index 000000000000..68ff7af5c5fb
--- /dev/null
+++ b/include/linux/frontswap.h
@@ -0,0 +1,127 @@
+#ifndef _LINUX_FRONTSWAP_H
+#define _LINUX_FRONTSWAP_H
+
+#include <linux/swap.h>
+#include <linux/mm.h>
+#include <linux/bitops.h>
+
+struct frontswap_ops {
+        void (*init)(unsigned);
+        int (*put_page)(unsigned, pgoff_t, struct page *);
+        int (*get_page)(unsigned, pgoff_t, struct page *);
+        void (*invalidate_page)(unsigned, pgoff_t);
+        void (*invalidate_area)(unsigned);
+};
+
+extern bool frontswap_enabled;
+extern struct frontswap_ops
+        frontswap_register_ops(struct frontswap_ops *ops);
+extern void frontswap_shrink(unsigned long);
+extern unsigned long frontswap_curr_pages(void);
+extern void frontswap_writethrough(bool);
+
+extern void __frontswap_init(unsigned type);
+extern int __frontswap_put_page(struct page *page);
+extern int __frontswap_get_page(struct page *page);
+extern void __frontswap_invalidate_page(unsigned, pgoff_t);
+extern void __frontswap_invalidate_area(unsigned);
+
+#ifdef CONFIG_FRONTSWAP
+
+static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
+{
+        bool ret = false;
+
+        if (frontswap_enabled && sis->frontswap_map)
+                ret = test_bit(offset, sis->frontswap_map);
+        return ret;
+}
+
+static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
+{
+        if (frontswap_enabled && sis->frontswap_map)
+                set_bit(offset, sis->frontswap_map);
+}
+
+static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
+{
+        if (frontswap_enabled && sis->frontswap_map)
+                clear_bit(offset, sis->frontswap_map);
+}
+
+static inline void frontswap_map_set(struct swap_info_struct *p,
+                                     unsigned long *map)
+{
+        p->frontswap_map = map;
+}
+
+static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
+{
+        return p->frontswap_map;
+}
+#else
+/* all inline routines become no-ops and all externs are ignored */
+
+#define frontswap_enabled (0)
+
+static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
+{
+        return false;
+}
+
+static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
+{
+}
+
+static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
+{
+}
+
+static inline void frontswap_map_set(struct swap_info_struct *p,
+                                     unsigned long *map)
+{
+}
+
+static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
+{
+        return NULL;
+}
+#endif
+
+static inline int frontswap_put_page(struct page *page)
+{
+        int ret = -1;
+
+        if (frontswap_enabled)
+                ret = __frontswap_put_page(page);
+        return ret;
+}
+
+static inline int frontswap_get_page(struct page *page)
+{
+        int ret = -1;
+
+        if (frontswap_enabled)
+                ret = __frontswap_get_page(page);
+        return ret;
+}
+
+static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
+{
+        if (frontswap_enabled)
+                __frontswap_invalidate_page(type, offset);
+}
+
+static inline void frontswap_invalidate_area(unsigned type)
+{
+        if (frontswap_enabled)
+                __frontswap_invalidate_area(type);
+}
+
+static inline void frontswap_init(unsigned type)
+{
+        if (frontswap_enabled)
+                __frontswap_init(type);
+}
+
+#endif /* _LINUX_FRONTSWAP_H */