[PATCH] page migration cleanup: pass "mapping" to migration functions

Change handling of address spaces.

Pass a pointer to the address space in which the page is migrated to all
migration function.  This avoids repeatedly having to retrieve the address
space pointer from the page and checking it for validity.  The old page
mapping will change once migration has gone to a certain step, so it is less
confusing to have the pointer always available.

Move the setting of the mapping and index for the new page into
migrate_pages().

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 8 insertions, 4 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index c823a3815e24..e917403f4d58 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -376,7 +376,8 @@ struct address_space_operations {
         struct page* (*get_xip_page)(struct address_space *, sector_t,
                         int);
         /* migrate the contents of a page to the specified target */
-        int (*migratepage) (struct page *, struct page *);
+        int (*migratepage) (struct address_space *,
+                        struct page *, struct page *);
 };
 
 struct backing_dev_info;
@@ -1772,7 +1773,8 @@ extern void simple_release_fs(struct vfsmount **mount, int *count);
 extern ssize_t simple_read_from_buffer(void __user *, size_t, loff_t *, const void *, size_t);
 
 #ifdef CONFIG_MIGRATION
-extern int buffer_migrate_page(struct page *, struct page *);
+extern int buffer_migrate_page(struct address_space *,
+                                struct page *, struct page *);
 #else
 #define buffer_migrate_page NULL
 #endif
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index e8d3b08cc354..287c47b5e5df 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -6,12 +6,14 @@
 #ifdef CONFIG_MIGRATION
 extern int isolate_lru_page(struct page *p, struct list_head *pagelist);
 extern int putback_lru_pages(struct list_head *l);
-extern int migrate_page(struct page *, struct page *);
+extern int migrate_page(struct address_space *,
+                        struct page *, struct page *);
 extern int migrate_pages(struct list_head *l, struct list_head *t,
                 struct list_head *moved, struct list_head *failed);
 extern int migrate_pages_to(struct list_head *pagelist,
                         struct vm_area_struct *vma, int dest);
-extern int fail_migrate_page(struct page *, struct page *);
+extern int fail_migrate_page(struct address_space *,
+                        struct page *, struct page *);
 
 extern int migrate_prep(void);