[PATCH] page migration reorg

Centralize the page migration functions in anticipation of additional
tinkering.  Creates a new file mm/migrate.c

1. Extract buffer_migrate_page() from fs/buffer.c

2. Extract central migration code from vmscan.c

3. Extract some components from mempolicy.c

4. Export pageout() and remove_from_swap() from vmscan.c

5. Make it possible to configure NUMA systems without page migration
   and non-NUMA systems with page migration.

I had to so some #ifdeffing in mempolicy.c that may need a cleanup.

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, 1 insertions, 62 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index a9b399402007..1d3683d496f8 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3051,68 +3051,6 @@ asmlinkage long sys_bdflush(int func, long data)
 }
 
 /*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist.
- */
-#ifdef CONFIG_MIGRATION
-int buffer_migrate_page(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);
-
-        head = page_buffers(page);
-
-        rc = migrate_page_remove_references(newpage, page, 3);
-        if (rc)
-                return rc;
-
-        bh = head;
-        do {
-                get_bh(bh);
-                lock_buffer(bh);
-                bh = bh->b_this_page;
-
-        } while (bh != head);
-
-        ClearPagePrivate(page);
-        set_page_private(newpage, page_private(page));
-        set_page_private(page, 0);
-        put_page(page);
-        get_page(newpage);
-
-        bh = head;
-        do {
-                set_bh_page(bh, newpage, bh_offset(bh));
-                bh = bh->b_this_page;
-
-        } while (bh != head);
-
-        SetPagePrivate(newpage);
-
-        migrate_page_copy(newpage, page);
-
-        bh = head;
-        do {
-                unlock_buffer(bh);
-                put_bh(bh);
-                bh = bh->b_this_page;
-
-        } while (bh != head);
-
-        return 0;
-}
-EXPORT_SYMBOL(buffer_migrate_page);
-#endif
-
-/*
  * Buffer-head allocation
  */
 static kmem_cache_t *bh_cachep;
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index bfb4f2917bb6..8cdfa4151659 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -29,6 +29,7 @@
 #include <linux/blkdev.h>
 #include <linux/hash.h>
 #include <linux/kthread.h>
+#include <linux/migrate.h>
 #include "xfs_linux.h"
 
 STATIC kmem_zone_t *xfs_buf_zone;