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authorChristoph Lameter <clameter@sgi.com>2006-02-01 03:05:41 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-01 08:53:17 -0800
commite965f9630c651fa4249039fd4b80c9392d07a856 (patch)
tree1353dd536d0ee549c30e462086624c21788ee9d2 /fs/buffer.c
parent7e2ab150d1b3b286a4c864c60a549b2601777b63 (diff)
[PATCH] Direct Migration V9: Avoid writeback / page_migrate() method
Migrate a page with buffers without requiring writeback This introduces a new address space operation migratepage() that may be used by a filesystem to implement its own version of page migration. A version is provided that migrates buffers attached to pages. Some filesystems (ext2, ext3, xfs) are modified to utilize this feature. The swapper address space operation are modified so that a regular migrate_page() will occur for anonymous pages without writeback (migrate_pages forces every anonymous page to have a swap entry). Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/buffer.c')
-rw-r--r--fs/buffer.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 3dc712f29d2..8bcbac87a28 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3050,6 +3050,66 @@ 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;
+
+ if (!mapping)
+ return -EAGAIN;
+
+ if (!page_has_buffers(page))
+ return migrate_page(newpage, page);
+
+ head = page_buffers(page);
+
+ if (migrate_page_remove_references(newpage, page, 3))
+ return -EAGAIN;
+
+ 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;