From: akpm@linux-foundation.org Subject: [patch 070/283] ext3: don't read inode block if the buffer has a write error Date: Fri, 25 Jul 2008 00:02:02 -0700 Message-ID: <200807250702.m6P722d6028480@imap1.linux-foundation.org> Cc: akpm@linux-foundation.org, hidehiro.kawai.ez@hitachi.com, jack@ucw.cz, linux-ext4@vger.kernel.org, nickpiggin@yahoo.com.au, satoshi.oshima.fk@hitachi.com, yumiko.sugita.yf@hitachi.com To: torvalds@linux-foundation.org Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:41951 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151AbYGYHCJ (ORCPT ); Fri, 25 Jul 2008 03:02:09 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Hidehiro Kawai A transient I/O error can corrupt inode data. Here is the scenario: (1) update inode_A at the block_B (2) pdflush writes out new inode_A to the filesystem, but it results in write I/O error, at this point, BH_Uptodate flag of the buffer for block_B is cleared and BH_Write_EIO is set (3) create new inode_C which located at block_B, and __ext3_get_inode_loc() tries to read on-disk block_B because the buffer is not uptodate (4) if it can read on-disk block_B successfully, inode_A is overwritten by old data This patch makes __ext3_get_inode_loc() not read the inode block if the buffer has BH_Write_EIO flag. In this case, the buffer should have the latest information, so setting the uptodate flag to the buffer (this avoids WARN_ON_ONCE() in mark_buffer_dirty().) According to this change, we would need to test BH_Write_EIO flag for the error checking. Currently nobody checks write I/O errors on metadata buffers, but it will be done in other patches I'm working on. Signed-off-by: Hidehiro Kawai Cc: sugita Cc: Satoshi OSHIMA Cc: Nick Piggin Cc: Jan Kara Cc: Signed-off-by: Andrew Morton --- fs/ext3/inode.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff -puN fs/ext3/inode.c~ext3-dont-read-inode-block-if-the-buffer-has-a-write-error fs/ext3/inode.c --- a/fs/ext3/inode.c~ext3-dont-read-inode-block-if-the-buffer-has-a-write-error +++ a/fs/ext3/inode.c @@ -2521,6 +2521,16 @@ static int __ext3_get_inode_loc(struct i } if (!buffer_uptodate(bh)) { lock_buffer(bh); + + /* + * If the buffer has the write error flag, we have failed + * to write out another inode in the same block. In this + * case, we don't have to read the block because we may + * read the old inode data successfully. + */ + if (buffer_write_io_error(bh) && !buffer_uptodate(bh)) + set_buffer_uptodate(bh); + if (buffer_uptodate(bh)) { /* someone brought it uptodate while we waited */ unlock_buffer(bh); _