2 files changed, 22 insertions, 7 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index b92b73d0b2b9..e694bd4434a4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -525,6 +525,7 @@ enum positive_aop_returns {
 struct page;
 struct address_space;
 struct writeback_control;
+enum migrate_mode;
 
 struct iov_iter {
         const struct iovec *iov;
@@ -614,7 +615,7 @@ struct address_space_operations {
          * is false, it must not block.
          */
         int (*migratepage) (struct address_space *,
-                        struct page *, struct page *, bool);
+                        struct page *, struct page *, enum migrate_mode);
         int (*launder_page) (struct page *);
         int (*is_partially_uptodate) (struct page *, read_descriptor_t *,
                                         unsigned long);
@@ -2540,7 +2541,8 @@ extern int generic_check_addressable(unsigned, u64);
 
 #ifdef CONFIG_MIGRATION
 extern int buffer_migrate_page(struct address_space *,
-                                struct page *, struct page *, bool);
+                                struct page *, struct page *,
+                                enum migrate_mode);
 #else
 #define buffer_migrate_page NULL
 #endif
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; }