1 files changed, 18 insertions, 5 deletions

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 14e6d2a88475..eaf867412f7a 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -6,18 +6,31 @@
 
 typedef struct page *new_page_t(struct page *, unsigned long private, int **);
 
+/*
+ * MIGRATE_ASYNC means never block
+ * MIGRATE_SYNC_LIGHT in the current implementation means to allow blocking
+ *      on most operations but not ->writepage as the potential stall time
+ *      is too significant
+ * MIGRATE_SYNC will block when migrating pages
+ */
+enum migrate_mode {
+        MIGRATE_ASYNC,
+        MIGRATE_SYNC_LIGHT,
+        MIGRATE_SYNC,
+};
+
 #ifdef CONFIG_MIGRATION
 #define PAGE_MIGRATION 1
 
 extern void putback_lru_pages(struct list_head *l);
 extern int migrate_page(struct address_space *,
-                        struct page *, struct page *, bool);
+                        struct page *, struct page *, enum migrate_mode);
 extern int migrate_pages(struct list_head *l, new_page_t x,
                         unsigned long private, bool offlining,
-                        bool sync);
+                        enum migrate_mode mode);
 extern int migrate_huge_pages(struct list_head *l, new_page_t x,
                         unsigned long private, bool offlining,
-                        bool sync);
+                        enum migrate_mode mode);
 
 extern int fail_migrate_page(struct address_space *,
                         struct page *, struct page *);
@@ -36,10 +49,10 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
 static inline void putback_lru_pages(struct list_head *l) {}
 static inline int migrate_pages(struct list_head *l, new_page_t x,
                 unsigned long private, bool offlining,
-                bool sync) { return -ENOSYS; }
+                enum migrate_mode mode) { return -ENOSYS; }
 static inline int migrate_huge_pages(struct list_head *l, new_page_t x,
                 unsigned long private, bool offlining,
-                bool sync) { return -ENOSYS; }
+                enum migrate_mode mode) { return -ENOSYS; }
 
 static inline int migrate_prep(void) { return -ENOSYS; }
 static inline int migrate_prep_local(void) { return -ENOSYS; }