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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 37331C55186 for ; Thu, 23 Apr 2020 23:17:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2109220780 for ; Thu, 23 Apr 2020 23:17:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728349AbgDWXGn (ORCPT ); Thu, 23 Apr 2020 19:06:43 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:48150 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727879AbgDWXG1 (ORCPT ); Thu, 23 Apr 2020 19:06:27 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1jRkvI-0004ZR-4F; Fri, 24 Apr 2020 00:06:24 +0100 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1jRkvH-00E6eu-L4; Fri, 24 Apr 2020 00:06:23 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Theodore Ts'o" , "Lukas Czerner" Date: Fri, 24 Apr 2020 00:03:57 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 010/245] ext4: wait for existing dio workers in ext4_alloc_file_blocks() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.83-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Czerner commit 0d306dcf86e8f065dff42a4a934ae9d99af35ba5 upstream. Currently existing dio workers can jump in and potentially increase extent tree depth while we're allocating blocks in ext4_alloc_file_blocks(). This may cause us to underestimate the number of credits needed for the transaction because the extent tree depth can change after our estimation. Fix this by waiting for all the existing dio workers in the same way as we do it in ext4_punch_hole. We've seen errors caused by this in xfstest generic/299, however it's really hard to reproduce. Signed-off-by: Lukas Czerner Signed-off-by: Theodore Ts'o Signed-off-by: Ben Hutchings --- fs/ext4/extents.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4707,6 +4707,10 @@ static int ext4_alloc_file_blocks(struct if (len <= EXT_UNWRITTEN_MAX_LEN) flags |= EXT4_GET_BLOCKS_NO_NORMALIZE; + /* Wait all existing dio workers, newcomers will block on i_mutex */ + ext4_inode_block_unlocked_dio(inode); + inode_dio_wait(inode); + /* * credits to insert 1 extent into extent tree */ @@ -4756,6 +4760,8 @@ retry: goto retry; } + ext4_inode_resume_unlocked_dio(inode); + return ret > 0 ? ret2 : ret; }