include/linux/migrate.h: remove migrate_page #define

This is designed to avoid a few ifdefs in .c files but it's obnoxious
because it can cause unsuspecting "migrate_page" symbols to get turned into
"NULL".

Just nuke it and use the ifdefs.

Cc: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 4 insertions, 3 deletions

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index a2901c414664..b66fd10f4b93 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -82,9 +82,6 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
         return -ENOSYS;
 }
 
-/* Possible settings for the migrate_page() method in address_operations */
-#define migrate_page NULL
-
 #endif /* CONFIG_MIGRATION */
 
 #ifdef CONFIG_NUMA_BALANCING
diff --git a/mm/shmem.c b/mm/shmem.c
index 469f90d56051..4fad61bb41e5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3077,7 +3077,9 @@ static const struct address_space_operations shmem_aops = {
         .write_begin    = shmem_write_begin,
         .write_end      = shmem_write_end,
 #endif
+#ifdef CONFIG_MIGRATION
         .migratepage    = migrate_page,
+#endif
         .error_remove_page = generic_error_remove_page,
 };
 
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 3e0ec83d000c..ef1f39139b71 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -28,7 +28,9 @@
 static const struct address_space_operations swap_aops = {
         .writepage      = swap_writepage,
         .set_page_dirty = swap_set_page_dirty,
+#ifdef CONFIG_MIGRATION
         .migratepage    = migrate_page,
+#endif
 };
 
 static struct backing_dev_info swap_backing_dev_info = {