From patchwork Thu Aug 19 06:57:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Yi X-Patchwork-Id: 1518466 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-ext4-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4GqwKX5NzGz9t1C for ; Thu, 19 Aug 2021 16:46:40 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231294AbhHSGrP (ORCPT ); Thu, 19 Aug 2021 02:47:15 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:17048 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231347AbhHSGrN (ORCPT ); Thu, 19 Aug 2021 02:47:13 -0400 Received: from dggeme752-chm.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GqwF66vCdzbfMl; Thu, 19 Aug 2021 14:42:50 +0800 (CST) Received: from huawei.com (10.175.127.227) by dggeme752-chm.china.huawei.com (10.3.19.98) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Thu, 19 Aug 2021 14:46:35 +0800 From: Zhang Yi To: CC: , , , , Subject: [PATCH v2 4/4] ext4: prevent getting empty inode buffer Date: Thu, 19 Aug 2021 14:57:04 +0800 Message-ID: <20210819065704.1248402-5-yi.zhang@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210819065704.1248402-1-yi.zhang@huawei.com> References: <20210819065704.1248402-1-yi.zhang@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggeme752-chm.china.huawei.com (10.3.19.98) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org In ext4_get_inode_loc(), we may skip IO and get an zero && uptodate inode buffer when the inode monopolize an inode block for performance reason. For most cases, ext4_mark_iloc_dirty() will fill the inode buffer to make it fine, but we could miss this call if something bad happened. Finally, __ext4_get_inode_loc_noinmem() may probably get an empty inode buffer and trigger ext4 error. For example, if we remove a nonexistent xattr on inode A, ext4_xattr_set_handle() will return ENODATA before invoking ext4_mark_iloc_dirty(), it will left an uptodate but zero buffer. We will get checksum error message in ext4_iget() when getting inode again. EXT4-fs error (device sda): ext4_lookup:1784: inode #131074: comm cat: iget: checksum invalid Even worse, if we allocate another inode B at the same inode block, it will corrupt the inode A on disk when write back inode B. So this patch postpone the init and mark buffer uptodate logic until before filling correct inode data in ext4_do_update_inode() if skip read I/O, ensure the buffer is real uptodate. Signed-off-by: Zhang Yi Reviewed-by: Jan Kara --- fs/ext4/inode.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d0d7a5295bf9..02d910c9d8f1 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4367,9 +4367,11 @@ static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino, } brelse(bitmap_bh); if (i == start + inodes_per_block) { - /* all other inodes are free, so skip I/O */ - memset(bh->b_data, 0, bh->b_size); - set_buffer_uptodate(bh); + /* + * All other inodes are free, skip I/O. Return + * un-inited buffer (which is postponed until + * before filling inode data) immediately. + */ unlock_buffer(bh); goto has_buffer; } @@ -5026,6 +5028,24 @@ static int ext4_do_update_inode(handle_t *handle, gid_t i_gid; projid_t i_projid; + /* + * If the buffer is not uptodate, it means all information of inode + * in memory and we got this buffer without reading the block. We + * must be cautious that once we mark the buffer as uptodate, we + * rely on filling in the correct inode data later in this function. + * Otherwise if we getting the left falsepositive buffer when + * creating other inode on the same block, it could corrupt the + * inode data on disk. + */ + if (!buffer_uptodate(bh)) { + lock_buffer(bh); + if (!buffer_uptodate(bh)) { + memset(bh->b_data, 0, bh->b_size); + set_buffer_uptodate(bh); + } + unlock_buffer(bh); + } + spin_lock(&ei->i_raw_lock); /* For fields not tracked in the in-memory inode,