Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932180Ab0ANKO7 (ORCPT ); Thu, 14 Jan 2010 05:14:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932093Ab0ANKO6 (ORCPT ); Thu, 14 Jan 2010 05:14:58 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:59334 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755021Ab0ANKO4 (ORCPT ); Thu, 14 Jan 2010 05:14:56 -0500 X-AuditID: b753bd60-aa251ba000001698-99-4b4eee9d7816 Message-ID: <4B4EEE86.7080807@hitachi.com> Date: Thu, 14 Jan 2010 19:14:30 +0900 From: Hidehiro Kawai User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; ja-JP; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: ja MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, Andrew Morton , Andreas Dilger , "Theodore Ts'o" , Jan Kara Cc: Nick Piggin , dle-develop@lists.sourceforge.net, Satoshi OSHIMA Subject: [PATCH] ext3: prevent reread after write IO error v2 References: <4B4EB5B9.4020809@hitachi.com> <4B4EDE5C.8040600@hitachi.com> In-Reply-To: <4B4EDE5C.8040600@hitachi.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== X-FMFTCR: RANGEC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3857 Lines: 124 This patch fixes the similar bug fixed by commit 95450f5a. If a directory is modified, its data block is journaled as metadata and finally written back to the right place. Now, we assume a transient write erorr happens on that writeback. Uptodate flag of the buffer is cleared by write error, so next access on the buffer causes a reread from disk. This means it breaks the filesystems consistency. To prevent old directory data from being reread, this patch set uptodate flag again in the case of after write error before issuing the read operation. The write error on the directory's data block is detected at the time of journal checkpointing or discarded if a rewrite by another modification succeeds, so no problem. Similarly, this kind of consistency breakage can be caused by a transient write error on a bitmap block. I tested this patch by using fault injection approach. By the way, I think the right fix is to keep uptodate flag on write error, but it gives a big impact. We have to confirm whether over 200 buffer_uptodate's are used for real uptodate check or write error check. For now, I adopt the quick-fix solution. Signed-off-by: Hidehiro Kawai --- fs/ext3/balloc.c | 12 ++++++++++++ fs/ext3/inode.c | 13 +++++++++++++ fs/ext3/namei.c | 15 ++++++++++++++- 3 files changed, 39 insertions(+), 1 deletions(-) diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c index 27967f9..5dc5ccf 100644 --- a/fs/ext3/balloc.c +++ b/fs/ext3/balloc.c @@ -156,6 +156,18 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group) if (likely(bh_uptodate_or_lock(bh))) return bh; + /* + * uptodate flag may have been cleared by a previous (transient) + * write IO error. In this case, we don't want to reread its + * old on-disk data. Actually the buffer has the latest data, + * so set uptodate flag again. + */ + if (buffer_write_io_error(bh)) { + set_buffer_uptodate(bh); + unlock_buffer(bh); + return bh; + } + if (bh_submit_read(bh) < 0) { brelse(bh); ext3_error(sb, __func__, diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index 455e6e6..67d7849 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -1077,10 +1077,23 @@ struct buffer_head *ext3_bread(handle_t *handle, struct inode *inode, return bh; if (buffer_uptodate(bh)) return bh; + + /* + * uptodate flag may have been cleared by a previous (transient) + * write IO error. In this case, we don't want to reread its + * old on-disk data. Actually the buffer has the latest data, + * so set uptodate flag again. + */ + if (buffer_write_io_error(bh)) { + set_buffer_uptodate(bh); + return bh; + } + ll_rw_block(READ_META, 1, &bh); wait_on_buffer(bh); if (buffer_uptodate(bh)) return bh; + put_bh(bh); *err = -EIO; return NULL; diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c index 7b0e44f..7ed8e45 100644 --- a/fs/ext3/namei.c +++ b/fs/ext3/namei.c @@ -909,7 +909,20 @@ restart: num++; bh = ext3_getblk(NULL, dir, b++, 0, &err); bh_use[ra_max] = bh; - if (bh) + if (!bh || buffer_uptodate(bh)) + continue; + + /* + * uptodate flag may have been cleared by a + * previous (transient) write IO error. In + * this case, we don't want to reread its + * old on-disk data. Actually the buffer + * has the latest data, so set uptodate flag + * again. + */ + if (buffer_write_io_error(bh)) + set_buffer_uptodate(bh); + else ll_rw_block(READ_META, 1, &bh); } } -- 1.6.0.3 -- Hidehiro Kawai Hitachi, Systems Development Laboratory Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/