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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9CCA9C433DB for ; Sat, 2 Jan 2021 05:14:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E5F9205CA for ; Sat, 2 Jan 2021 05:14:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726306AbhABFOn (ORCPT ); Sat, 2 Jan 2021 00:14:43 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:43174 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725981AbhABFOn (ORCPT ); Sat, 2 Jan 2021 00:14:43 -0500 Received: from localhost (unknown [IPv6:2804:431:c7f4:46f8:ae05:b936:9029:cd4b]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: krisman) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id C034B1F45010; Sat, 2 Jan 2021 05:14:00 +0000 (GMT) From: Gabriel Krisman Bertazi To: Mauricio Faria de Oliveira Cc: Jens Axboe , linux-block@vger.kernel.org Subject: Re: [PATCH] loop: fix I/O error on fsync() in detached loop devices Organization: Collabora References: <20201231162845.1853347-1-mfo@canonical.com> Date: Sat, 02 Jan 2021 02:13:53 -0300 In-Reply-To: <20201231162845.1853347-1-mfo@canonical.com> (Mauricio Faria de Oliveira's message of "Thu, 31 Dec 2020 13:28:45 -0300") Message-ID: <87k0sv6hv2.fsf@collabora.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Mauricio Faria de Oliveira writes: > There's an I/O error on fsync() in a detached loop device > if it has been previously attached. > > The issue is write cache is enabled in the attach path in > loop_configure() but it isn't disabled in the detach path; > thus it remains enabled in the block device regardless of > whether it is attached or not. > > Now fsync() can get an I/O request that will just be failed > later in loop_queue_rq() as device's state is not 'Lo_bound'. > > So, disable write cache in the detach path. > > Test-case: > > # DEV=/dev/loop7 > > # IMG=/tmp/image > # truncate --size 1M $IMG > > # losetup $DEV $IMG > # losetup -d $DEV > > Before: > > # strace -e fsync parted -s $DEV print 2>&1 | grep fsync > fsync(3) = -1 EIO (Input/output error) > Warning: Error fsyncing/closing /dev/loop7: Input/output error > [ 982.529929] blk_update_request: I/O error, dev loop7, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0 > > After: > > # strace -e fsync parted -s $DEV print 2>&1 | grep fsync > fsync(3) = 0 > > Signed-off-by: Mauricio Faria de Oliveira > Co-developed-by: Eric Desrochers > Signed-off-by: Eric Desrochers This sign-off chain is not sorted correctly. See Documentation/process/submitting-patches.rst. Other than that, I think the fix makes sense. Tested-by: Gabriel Krisman Bertazi > --- > drivers/block/loop.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index e5ff328f0917..49517482e061 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -1212,6 +1212,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release) > goto out_unlock; > } > > + if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && filp->f_op->fsync) > + blk_queue_write_cache(lo->lo_queue, false, false); > + > /* freeze request queue during the transition */ > blk_mq_freeze_queue(lo->lo_queue); -- Gabriel Krisman Bertazi