From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFF10C04A6B for ; Mon, 6 May 2019 13:49:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B798206BF for ; Mon, 6 May 2019 13:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726046AbfEFNt4 (ORCPT ); Mon, 6 May 2019 09:49:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41408 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725852AbfEFNtz (ORCPT ); Mon, 6 May 2019 09:49:55 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DA81E308A9E2 for ; Mon, 6 May 2019 13:49:55 +0000 (UTC) Received: from localhost.localdomain (unknown [10.40.205.118]) by smtp.corp.redhat.com (Postfix) with ESMTP id 367035D969 for ; Mon, 6 May 2019 13:49:55 +0000 (UTC) From: Lukas Czerner To: linux-ext4@vger.kernel.org Subject: [PATCH] ext4: Fix data corruption caused by overlapping unaligned and aligned IO Date: Mon, 6 May 2019 15:49:52 +0200 Message-Id: <20190506134952.26070-1-lczerner@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Mon, 06 May 2019 13:49:55 +0000 (UTC) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Unaligned AIO must be serialized because the zeroing of partial blocks of unaligned AIO can result in data corruption in case it's overlapping another in flight IO. Currently we wait for all unwritten extents before we submit unaligned AIO which protects data in case of unaligned AIO is following overlapping IO. However if a unaligned AIO is followed by overlapping aligned AIO we can still end up corrupting data. To fix this, we must make sure that the unaligned AIO is the only IO in flight by waiting for unwritten extents conversion not just before the IO submission, but right after it as well. This problem can be reproduced by xfstest generic/538 Signed-off-by: Lukas Czerner --- fs/ext4/file.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 98ec11f69cd4..2c5baa5e8291 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -264,6 +264,13 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) } ret = __generic_file_write_iter(iocb, from); + /* + * Unaligned direct AIO must be the only IO in flight. Otherwise + * overlapping aligned IO after unaligned might result in data + * corruption. + */ + if (ret == -EIOCBQUEUED && unaligned_aio) + ext4_unwritten_wait(inode); inode_unlock(inode); if (ret > 0) -- 2.20.1