From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765342AbXEVCip (ORCPT ); Mon, 21 May 2007 22:38:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759280AbXEVCii (ORCPT ); Mon, 21 May 2007 22:38:38 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:50417 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759207AbXEVCih (ORCPT ); Mon, 21 May 2007 22:38:37 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrew Morton Cc: Linus Torvalds , , Nick Piggin Subject: [PATCH 2/3] rd: Mark ramdisk buffer heads dirty in ramdisk_set_page_dirty References: Date: Mon, 21 May 2007 20:36:51 -0600 In-Reply-To: (Eric W. Biederman's message of "Mon, 21 May 2007 20:31:50 -0600") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org The problem: When we are trying to free buffers try_to_free_buffers will look at ramdisk pages with clean buffer heads and remove the dirty bit from the page. Resulting in ramdisk pages with data that get removed from the page cache. Ouch! When we mark a ramdisk page dirty we call set_page_dirty which then calls ramdisk_set_page_dirty. Currently we don't mark the buffer heads dirty leaving us susceptible to the problem above. So to fix the mismatch between buffer head state and page state this patch modifies ramdisk_set_page_dirty to set the dirty bit on all of the buffers a page may posses. I set the uptodate bit on the buffer head so that later we can use simple_commit_write, and because it is trivially safe. Signed-off-by: Eric W. Biederman --- drivers/block/rd.c | 15 +++++++++++++++ 1 files changed, 15 insertions(+), 0 deletions(-) diff --git a/drivers/block/rd.c b/drivers/block/rd.c index a1512da..41de0f4 100644 --- a/drivers/block/rd.c +++ b/drivers/block/rd.c @@ -184,6 +184,21 @@ static int ramdisk_writepages(struct address_space *mapping, */ static int ramdisk_set_page_dirty(struct page *page) { + struct address_space * const mapping = page_mapping(page); + + spin_lock(&mapping->private_lock); + if (page_has_buffers(page)) { + struct buffer_head *head = page_buffers(page); + struct buffer_head *bh = head; + + do { + set_buffer_uptodate(bh); + set_buffer_dirty(bh); + bh = bh->b_this_page; + } while (bh != head); + } + spin_unlock(&mapping->private_lock); + if (!TestSetPageDirty(page)) return 1; return 0; -- 1.5.1.1.181.g2de0