From patchwork Wed Oct 10 10:04:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 10634293 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 250FC69C1 for ; Wed, 10 Oct 2018 10:04:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 104A12960A for ; Wed, 10 Oct 2018 10:04:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 04FC129627; Wed, 10 Oct 2018 10:04:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 952022960A for ; Wed, 10 Oct 2018 10:04:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726861AbeJJRZv (ORCPT ); Wed, 10 Oct 2018 13:25:51 -0400 Received: from mx2.suse.de ([195.135.220.15]:34954 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727007AbeJJRZv (ORCPT ); Wed, 10 Oct 2018 13:25:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C5C39B057; Wed, 10 Oct 2018 10:04:21 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id A06EA1E3AA4; Wed, 10 Oct 2018 12:04:18 +0200 (CEST) From: Jan Kara To: Jens Axboe Cc: , Tetsuo Handa , Jan Kara Subject: [PATCH 07/15] loop: Push loop_ctl_mutex down into loop_clr_fd() Date: Wed, 10 Oct 2018 12:04:07 +0200 Message-Id: <20181010100415.26525-8-jack@suse.cz> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20181010100415.26525-1-jack@suse.cz> References: <20181010100415.26525-1-jack@suse.cz> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- drivers/block/loop.c | 49 +++++++++++++++++++++++++++++-------------------- 1 file changed, 29 insertions(+), 20 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 2410921bd9ff..be41d5dcecd2 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1028,15 +1028,22 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 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_device *lo) 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_device *lo) * 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_device *lo) 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 *bdev, fmode_t mode, 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 @@ static int lo_open(struct block_device *bdev, fmode_t mode) 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 *disk, fmode_t mode) 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,