[PATCH] SwapMig: CONFIG_MIGRATION fixes

Move move_to_lru, putback_lru_pages and isolate_lru in section surrounded by
CONFIG_MIGRATION saving some codesize for single processor kernels.

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, 77 insertions, 78 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 117add066f00..997d838f0e70 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -175,10 +175,9 @@ extern int try_to_free_pages(struct zone **, gfp_t);
 extern int shrink_all_memory(int);
 extern int vm_swappiness;
 
+#ifdef CONFIG_MIGRATION
 extern int isolate_lru_page(struct page *p);
 extern int putback_lru_pages(struct list_head *l);
-
-#ifdef CONFIG_MIGRATION
 extern int migrate_pages(struct list_head *l, struct list_head *t);
 #endif
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 58270aea669a..daed4a73b761 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -569,6 +569,40 @@ keep:
 }
 
 #ifdef CONFIG_MIGRATION
+static inline void move_to_lru(struct page *page)
+{
+        list_del(&page->lru);
+        if (PageActive(page)) {
+                /*
+                 * lru_cache_add_active checks that
+                 * the PG_active bit is off.
+                 */
+                ClearPageActive(page);
+                lru_cache_add_active(page);
+        } else {
+                lru_cache_add(page);
+        }
+        put_page(page);
+}
+
+/*
+ * Add isolated pages on the list back to the LRU
+ *
+ * returns the number of pages put back.
+ */
+int putback_lru_pages(struct list_head *l)
+{
+        struct page *page;
+        struct page *page2;
+        int count = 0;
+
+        list_for_each_entry_safe(page, page2, l, lru) {
+                move_to_lru(page);
+                count++;
+        }
+        return count;
+}
+
 /*
  * swapout a single page
  * page is locked upon entry, unlocked on exit
@@ -709,6 +743,48 @@ retry_later:
 
         return nr_failed + retry;
 }
+
+static void lru_add_drain_per_cpu(void *dummy)
+{
+        lru_add_drain();
+}
+
+/*
+ * Isolate one page from the LRU lists and put it on the
+ * indicated list. Do necessary cache draining if the
+ * page is not on the LRU lists yet.
+ *
+ * Result:
+ *  0 = page not on LRU list
+ *  1 = page removed from LRU list and added to the specified list.
+ * -ENOENT = page is being freed elsewhere.
+ */
+int isolate_lru_page(struct page *page)
+{
+        int rc = 0;
+        struct zone *zone = page_zone(page);
+
+redo:
+        spin_lock_irq(&zone->lru_lock);
+        rc = __isolate_lru_page(page);
+        if (rc == 1) {
+                if (PageActive(page))
+                        del_page_from_active_list(zone, page);
+                else
+                        del_page_from_inactive_list(zone, page);
+        }
+        spin_unlock_irq(&zone->lru_lock);
+        if (rc == 0) {
+                /*
+                 * Maybe this page is still waiting for a cpu to drain it
+                 * from one of the lru lists?
+                 */
+                rc = schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
+                if (rc == 0 && PageLRU(page))
+                        goto redo;
+        }
+        return rc;
+}
 #endif
 
 /*
@@ -758,48 +834,6 @@ static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
         return nr_taken;
 }
 
-static void lru_add_drain_per_cpu(void *dummy)
-{
-        lru_add_drain();
-}
-
-/*
- * Isolate one page from the LRU lists and put it on the
- * indicated list. Do necessary cache draining if the
- * page is not on the LRU lists yet.
- *
- * Result:
- *  0 = page not on LRU list
- *  1 = page removed from LRU list and added to the specified list.
- * -ENOENT = page is being freed elsewhere.
- */
-int isolate_lru_page(struct page *page)
-{
-        int rc = 0;
-        struct zone *zone = page_zone(page);
-
-redo:
-        spin_lock_irq(&zone->lru_lock);
-        rc = __isolate_lru_page(page);
-        if (rc == 1) {
-                if (PageActive(page))
-                        del_page_from_active_list(zone, page);
-                else
-                        del_page_from_inactive_list(zone, page);
-        }
-        spin_unlock_irq(&zone->lru_lock);
-        if (rc == 0) {
-                /*
-                 * Maybe this page is still waiting for a cpu to drain it
-                 * from one of the lru lists?
-                 */
-                rc = schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
-                if (rc == 0 && PageLRU(page))
-                        goto redo;
-        }
-        return rc;
-}
-
 /*
  * shrink_cache() adds the number of pages reclaimed to sc->nr_reclaimed
  */
@@ -865,40 +899,6 @@ done:
         pagevec_release(&pvec);
 }
 
-static inline void move_to_lru(struct page *page)
-{
-        list_del(&page->lru);
-        if (PageActive(page)) {
-                /*
-                 * lru_cache_add_active checks that
-                 * the PG_active bit is off.
-                 */
-                ClearPageActive(page);
-                lru_cache_add_active(page);
-        } else {
-                lru_cache_add(page);
-        }
-        put_page(page);
-}
-
-/*
- * Add isolated pages on the list back to the LRU
- *
- * returns the number of pages put back.
- */
-int putback_lru_pages(struct list_head *l)
-{
-        struct page *page;
-        struct page *page2;
-        int count = 0;
-
-        list_for_each_entry_safe(page, page2, l, lru) {
-                move_to_lru(page);
-                count++;
-        }
-        return count;
-}
-
 /*
  * This moves pages from the active list to the inactive list.
  *