1 files changed, 53 insertions, 0 deletions

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 87b9d14c710d..ec639aa3a1d3 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -67,3 +67,56 @@ static inline pte_t swp_entry_to_pte(swp_entry_t entry)
         BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
         return __swp_entry_to_pte(arch_entry);
 }
+
+#ifdef CONFIG_MIGRATION
+static inline swp_entry_t make_migration_entry(struct page *page, int write)
+{
+        BUG_ON(!PageLocked(page));
+        return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
+                        page_to_pfn(page));
+}
+
+static inline int is_migration_entry(swp_entry_t entry)
+{
+        return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
+                        swp_type(entry) == SWP_MIGRATION_WRITE);
+}
+
+static inline int is_write_migration_entry(swp_entry_t entry)
+{
+        return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
+}
+
+static inline struct page *migration_entry_to_page(swp_entry_t entry)
+{
+        struct page *p = pfn_to_page(swp_offset(entry));
+        /*
+         * Any use of migration entries may only occur while the
+         * corresponding page is locked
+         */
+        BUG_ON(!PageLocked(p));
+        return p;
+}
+
+static inline void make_migration_entry_read(swp_entry_t *entry)
+{
+        *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
+}
+
+extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+                                        unsigned long address);
+#else
+
+#define make_migration_entry(page, write) swp_entry(0, 0)
+#define is_migration_entry(swp) 0
+#define migration_entry_to_page(swp) NULL
+static inline void make_migration_entry_read(swp_entry_t *entryp) { }
+static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
+                                         unsigned long address) { }
+static inline int is_write_migration_entry(swp_entry_t entry)
+{
+        return 0;
+}
+
+#endif
+