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=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=unavailable 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 5C26AC43381 for ; Fri, 22 Feb 2019 14:07:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A55F207E0 for ; Fri, 22 Feb 2019 14:07:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="GfF1/8sM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726987AbfBVOHb (ORCPT ); Fri, 22 Feb 2019 09:07:31 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:43428 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726131AbfBVOHa (ORCPT ); Fri, 22 Feb 2019 09:07:30 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1ME43i5017338; Fri, 22 Feb 2019 14:07:24 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2018-07-02; bh=9B34j/FS9yVPGPhkLyq9uZEJGnTRNxE6DDWvhz4b2ZI=; b=GfF1/8sMjHybbmrXfdCNMHZufaysJZWOxy9bjKfTW/Re/gwb4W1ezAvF5k+WtN+nSShj kbHA3Q3E4hlhl0nr3Tjq7ih8CJSSL0cBfIwQFAwVzpS/mk9ojdrgbWN+cNNDWJEkCh/+ bE8gkcCb4X90dZCQ2Ig98dTXWde8xFJ3PZP1W9gxfellxvyTGPz4x0Nj+gZCjwuyBExK Duw9o2LHDvn9xbeMl9IWa/P1ICDzHcJGZeLDpxx61RTENYWGUixIHgWSwXU3MrnOYDKX cFGqVjDJkuWmf5M6dbVBLur3ifh9d+AAy3xKLn0U3Jxmj493Y+34hhfuXaiwHp120fm1 6w== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2qpb5ryapf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Feb 2019 14:07:24 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x1ME7Ioo025381 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Feb 2019 14:07:19 GMT Received: from abhmp0022.oracle.com (abhmp0022.oracle.com [141.146.116.28]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x1ME7IkL009336; Fri, 22 Feb 2019 14:07:18 GMT Received: from linux.cn.oracle.com (/10.182.69.106) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 22 Feb 2019 06:07:18 -0800 From: Dongli Zhang To: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jack@suse.cz Subject: [PATCH v3 2/2] loop: set GENHD_FL_NO_PART_SCAN after blkdev_reread_part() Date: Fri, 22 Feb 2019 22:10:20 +0800 Message-Id: <1550844620-6550-3-git-send-email-dongli.zhang@oracle.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1550844620-6550-1-git-send-email-dongli.zhang@oracle.com> References: <1550844620-6550-1-git-send-email-dongli.zhang@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9174 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902220100 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Commit 0da03cab87e6 ("loop: Fix deadlock when calling blkdev_reread_part()") moves blkdev_reread_part() out of the loop_ctl_mutex. However, GENHD_FL_NO_PART_SCAN is set before __blkdev_reread_part(). As a result, __blkdev_reread_part() will fail the check of GENHD_FL_NO_PART_SCAN and will not rescan the loop device to delete all partitions. Below are steps to reproduce the issue: step1 # dd if=/dev/zero of=tmp.raw bs=1M count=100 step2 # losetup -P /dev/loop0 tmp.raw step3 # parted /dev/loop0 mklabel gpt step4 # parted -a none -s /dev/loop0 mkpart primary 64s 1 step5 # losetup -d /dev/loop0 Step5 will not be able to delete /dev/loop0p1 (introduced by step4) and there is below kernel warning message: [ 464.414043] __loop_clr_fd: partition scan of loop0 failed (rc=-22) This patch sets GENHD_FL_NO_PART_SCAN after blkdev_reread_part(). Fixes: 0da03cab87e6 ("loop: Fix deadlock when calling blkdev_reread_part()") Signed-off-by: Dongli Zhang Reviewed-by: Jan Kara --- Changed since v1: * move the setting of lo->lo_state to Lo_unbound after partscan has finished as well (suggested by Jan Kara) Changed since v2: * Put the code inline in __loop_clr_fd() but not introduce new function (suggested by Jan Kara) drivers/block/loop.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 7908673..7ec3297 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1089,16 +1089,12 @@ static int __loop_clr_fd(struct loop_device *lo, bool release) kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); } mapping_set_gfp_mask(filp->f_mapping, gfp); - lo->lo_state = Lo_unbound; /* This is safe: open() is still holding a reference. */ module_put(THIS_MODULE); blk_mq_unfreeze_queue(lo->lo_queue); partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev; lo_number = lo->lo_number; - lo->lo_flags = 0; - if (!part_shift) - lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; loop_unprepare_queue(lo); out_unlock: mutex_unlock(&loop_ctl_mutex); @@ -1121,6 +1117,23 @@ static int __loop_clr_fd(struct loop_device *lo, bool release) /* Device is gone, no point in returning error */ err = 0; } + + /* + * lo->lo_state is set to Lo_unbound here after above partscan has + * finished. + * + * There cannot be anybody else entering __loop_clr_fd() as + * lo->lo_backing_file is already cleared and Lo_rundown state + * protects us from all the other places trying to change the 'lo' + * device. + */ + mutex_lock(&loop_ctl_mutex); + lo->lo_flags = 0; + if (!part_shift) + lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; + lo->lo_state = Lo_unbound; + mutex_unlock(&loop_ctl_mutex); + /* * Need not hold loop_ctl_mutex to fput backing file. * Calling fput holding loop_ctl_mutex triggers a circular -- 2.7.4