From e965f9630c651fa4249039fd4b80c9392d07a856 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 1 Feb 2006 03:05:41 -0800 Subject: [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 Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/buffer.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) (limited to 'fs/buffer.c') diff --git a/fs/buffer.c b/fs/buffer.c index 3dc712f29d2d..8bcbac87a28c 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3049,6 +3049,66 @@ asmlinkage long sys_bdflush(int func, long data) return 0; } +/* + * 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 */ -- cgit v1.2.3-59-g8ed1b