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

[deliverable/linux.git] / mm / migrate.c

diff --git a/mm/migrate.c b/mm/migrate.c
index 8095c607a494d11582500fed427bea090710443b..f65e69d9452711a12e00897dd4e00733fbb863d0 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -173,15 +173,11 @@ retry:
  * 2 for pages with a mapping
  * 3 for pages with a mapping and PagePrivate set.
  */
-static int migrate_page_move_mapping(struct page *newpage,
-                               struct page *page)
+static int migrate_page_move_mapping(struct address_space *mapping,
+               struct page *newpage, struct page *page)
 {
-       struct address_space *mapping = page_mapping(page);
        struct page **radix_pointer;
 
-       if (!mapping)
-               return -EAGAIN;
-
        write_lock_irq(&mapping->tree_lock);
 
        radix_pointer = (struct page **)radix_tree_lookup_slot(
@@ -197,15 +193,8 @@ static int migrate_page_move_mapping(struct page *newpage,
 
        /*
         * Now we know that no one else is looking at the page.
-        *
-        * Certain minimal information about a page must be available
-        * in order for other subsystems to properly handle the page if they
-        * find it through the radix tree update before we are finished
-        * copying the page.
         */
        get_page(newpage);
-       newpage->index = page->index;
-       newpage->mapping = page->mapping;
        if (PageSwapCache(page)) {
                SetPageSwapCache(newpage);
                set_page_private(newpage, page_private(page));
@@ -262,7 +251,8 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
  ***********************************************************/
 
 /* Always fail migration. Used for mappings that are not movable */
-int fail_migrate_page(struct page *newpage, struct page *page)
+int fail_migrate_page(struct address_space *mapping,
+                       struct page *newpage, struct page *page)
 {
        return -EIO;
 }
@@ -274,13 +264,14 @@ EXPORT_SYMBOL(fail_migrate_page);
  *
  * Pages are locked upon entry and exit.
  */
-int migrate_page(struct page *newpage, struct page *page)
+int migrate_page(struct address_space *mapping,
+               struct page *newpage, struct page *page)
 {
        int rc;
 
        BUG_ON(PageWriteback(page));    /* Writeback must be complete */
 
-       rc = migrate_page_move_mapping(newpage, page);
+       rc = migrate_page_move_mapping(mapping, newpage, page);
 
        if (rc)
                return rc;
@@ -305,21 +296,18 @@ EXPORT_SYMBOL(migrate_page);
  * if the underlying filesystem guarantees that no other references to "page"
  * exist.
  */
-int buffer_migrate_page(struct page *newpage, struct page *page)
+int buffer_migrate_page(struct address_space *mapping,
+               struct page *newpage, struct page *page)
 {
-       struct address_space *mapping = page->mapping;
        struct buffer_head *bh, *head;
        int rc;
 
-       if (!mapping)
-               return -EAGAIN;
-
        if (!page_has_buffers(page))
-               return migrate_page(newpage, page);
+               return migrate_page(mapping, newpage, page);
 
        head = page_buffers(page);
 
-       rc = migrate_page_move_mapping(newpage, page);
+       rc = migrate_page_move_mapping(mapping, newpage, page);
 
        if (rc)
                return rc;
@@ -448,9 +436,6 @@ redo:
                        goto next;
                }
 
-               newpage = lru_to_page(to);
-               lock_page(newpage);
-
                /*
                 * Establish swap ptes for anonymous pages or destroy pte
                 * maps for files.
@@ -473,11 +458,18 @@ redo:
                rc = -EPERM;
                if (try_to_unmap(page, 1) == SWAP_FAIL)
                        /* A vma has VM_LOCKED set -> permanent failure */
-                       goto unlock_both;
+                       goto unlock_page;
 
                rc = -EAGAIN;
                if (page_mapped(page))
-                       goto unlock_both;
+                       goto unlock_page;
+
+               newpage = lru_to_page(to);
+               lock_page(newpage);
+               /* Prepare mapping for the new page.*/
+               newpage->index = page->index;
+               newpage->mapping = page->mapping;
+
                /*
                 * Pages are properly locked and writeback is complete.
                 * Try to migrate the page.
@@ -494,7 +486,8 @@ redo:
                         * own migration function. This is the most common
                         * path for page migration.
                         */
-                       rc = mapping->a_ops->migratepage(newpage, page);
+                       rc = mapping->a_ops->migratepage(mapping,
+                                                       newpage, page);
                        goto unlock_both;
                 }
 
@@ -524,7 +517,7 @@ redo:
                 */
                if (!page_has_buffers(page) ||
                    try_to_release_page(page, GFP_KERNEL)) {
-                       rc = migrate_page(newpage, page);
+                       rc = migrate_page(mapping, newpage, page);
                        goto unlock_both;
                }
 
@@ -553,12 +546,17 @@ unlock_page:
                unlock_page(page);
 
 next:
-               if (rc == -EAGAIN) {
-                       retry++;
-               } else if (rc) {
-                       /* Permanent failure */
-                       list_move(&page->lru, failed);
-                       nr_failed++;
+               if (rc) {
+                       if (newpage)
+                               newpage->mapping = NULL;
+
+                       if (rc == -EAGAIN)
+                               retry++;
+                       else {
+                               /* Permanent failure */
+                               list_move(&page->lru, failed);
+                               nr_failed++;
+                       }
                } else {
                        if (newpage) {
                                /* Successful migration. Return page to LRU */