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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 6CBE4C2F3A0 for ; Mon, 21 Jan 2019 14:03:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3801D21019 for ; Mon, 21 Jan 2019 14:03:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079398; bh=rCbwB7vVAtEaRAzs8l7W6vU0J1n3cvQJ54V51eC9XqI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=b/NzW/Q5l9fanNGtfSWAu/NsRDMbzNx8UfJNm8XbdE65hKC7/GpN7rABMrOn7fqTc jqBPtXASTYZ5ktxVl4f2squkqvbe6MNSopG1bOr4i+1KzuFuBDOHzS9iJ8Q6CydVri 6eTxb+vbTKyKwwCuSlXm5i1LvpJTyRdPAsYA0wys= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732943AbfAUODK (ORCPT ); Mon, 21 Jan 2019 09:03:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:50952 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732919AbfAUODF (ORCPT ); Mon, 21 Jan 2019 09:03:05 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E9BC22089F; Mon, 21 Jan 2019 14:03:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079384; bh=rCbwB7vVAtEaRAzs8l7W6vU0J1n3cvQJ54V51eC9XqI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d+QKpdqh/deg1fZ3mAH+ckHnGZqymgfdPKq+ytS+FRZCc6XwzBlR78DcqodPk3tKC LZxD9TN38JmMOsiVFd0JCYSAiamBwKsfkEoAFNCeJ+PXrmO6EahiQRCzGopWuu9i59 safW7eUXUo0ZUek2znm2KQUmT1ateLRFwQdNI8Qc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kara , Jens Axboe Subject: [PATCH 4.19 86/99] loop: Push loop_ctl_mutex down into loop_clr_fd() Date: Mon, 21 Jan 2019 14:49:18 +0100 Message-Id: <20190121134917.434547729@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190121134913.924726465@linuxfoundation.org> References: <20190121134913.924726465@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit 7ccd0791d98531df7cd59e92d55e4f063d48a070 upstream. loop_clr_fd() has a weird locking convention that is expects loop_ctl_mutex held, releases it on success and keeps it on failure. Untangle the mess by moving locking of loop_ctl_mutex into loop_clr_fd(). Signed-off-by: Jan Kara Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/loop.c | 49 +++++++++++++++++++++++++++++-------------------- 1 file changed, 29 insertions(+), 20 deletions(-) --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1028,15 +1028,22 @@ loop_init_xfer(struct loop_device *lo, s static int __loop_clr_fd(struct loop_device *lo) { - struct file *filp = lo->lo_backing_file; + struct file *filp = NULL; gfp_t gfp = lo->old_gfp_mask; struct block_device *bdev = lo->lo_device; + int err = 0; - if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) - return -ENXIO; + mutex_lock(&loop_ctl_mutex); + if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) { + err = -ENXIO; + goto out_unlock; + } - if (filp == NULL) - return -EINVAL; + filp = lo->lo_backing_file; + if (filp == NULL) { + err = -EINVAL; + goto out_unlock; + } /* freeze request queue during the transition */ blk_mq_freeze_queue(lo->lo_queue); @@ -1083,6 +1090,7 @@ static int __loop_clr_fd(struct loop_dev if (!part_shift) lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; loop_unprepare_queue(lo); +out_unlock: mutex_unlock(&loop_ctl_mutex); /* * Need not hold loop_ctl_mutex to fput backing file. @@ -1090,14 +1098,22 @@ static int __loop_clr_fd(struct loop_dev * lock dependency possibility warning as fput can take * bd_mutex which is usually taken before loop_ctl_mutex. */ - fput(filp); - return 0; + if (filp) + fput(filp); + return err; } static int loop_clr_fd(struct loop_device *lo) { - if (lo->lo_state != Lo_bound) + int err; + + err = mutex_lock_killable_nested(&loop_ctl_mutex, 1); + if (err) + return err; + if (lo->lo_state != Lo_bound) { + mutex_unlock(&loop_ctl_mutex); return -ENXIO; + } /* * If we've explicitly asked to tear down the loop device, * and it has an elevated reference count, set it for auto-teardown when @@ -1114,6 +1130,7 @@ static int loop_clr_fd(struct loop_devic return 0; } lo->lo_state = Lo_rundown; + mutex_unlock(&loop_ctl_mutex); return __loop_clr_fd(lo); } @@ -1448,14 +1465,7 @@ static int lo_ioctl(struct block_device mutex_unlock(&loop_ctl_mutex); break; case LOOP_CLR_FD: - err = mutex_lock_killable_nested(&loop_ctl_mutex, 1); - if (err) - return err; - /* loop_clr_fd would have unlocked loop_ctl_mutex on success */ - err = loop_clr_fd(lo); - if (err) - mutex_unlock(&loop_ctl_mutex); - break; + return loop_clr_fd(lo); case LOOP_SET_STATUS: err = -EPERM; if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) { @@ -1691,7 +1701,6 @@ out: static void lo_release(struct gendisk *disk, fmode_t mode) { struct loop_device *lo; - int err; mutex_lock(&loop_ctl_mutex); lo = disk->private_data; @@ -1702,13 +1711,13 @@ static void lo_release(struct gendisk *d if (lo->lo_state != Lo_bound) goto out_unlock; lo->lo_state = Lo_rundown; + mutex_unlock(&loop_ctl_mutex); /* * In autoclear mode, stop the loop thread * and remove configuration after last close. */ - err = __loop_clr_fd(lo); - if (!err) - return; + __loop_clr_fd(lo); + return; } else if (lo->lo_state == Lo_bound) { /* * Otherwise keep thread (if running) and config,