mm/rmap: make rmap_walk to get the rmap_walk_control argument

In each rmap traverse case, there is some difference so that we need
function pointers and arguments to them in order to handle these

For this purpose, struct rmap_walk_control is introduced in this patch,
and will be extended in following patch.  Introducing and extending are
separate, because it clarify changes.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 10 insertions, 6 deletions

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 45c9b6a17bcb..0eef8cb0baf7 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -76,8 +76,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
 int page_referenced_ksm(struct page *page,
                         struct mem_cgroup *memcg, unsigned long *vm_flags);
 int try_to_unmap_ksm(struct page *page, enum ttu_flags flags);
-int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
-                  struct vm_area_struct *, unsigned long, void *), void *arg);
+int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
 void ksm_migrate_page(struct page *newpage, struct page *oldpage);
 
 #else  /* !CONFIG_KSM */
@@ -120,8 +119,8 @@ static inline int try_to_unmap_ksm(struct page *page, enum ttu_flags flags)
         return 0;
 }
 
-static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page*,
-                struct vm_area_struct *, unsigned long, void *), void *arg)
+static inline int rmap_walk_ksm(struct page *page,
+                        struct rmap_walk_control *rwc)
 {
         return 0;
 }
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6dacb93a6d94..6a456ce6de20 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page);
 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 
+struct rmap_walk_control {
+        void *arg;
+        int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
+                                        unsigned long addr, void *arg);
+};
+
 /*
  * Called by migrate.c to remove migration ptes, but might be used more later.
  */
-int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
-                struct vm_area_struct *, unsigned long, void *), void *arg);
+int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
 
 #else   /* !CONFIG_MMU */