From patchwork Thu Sep 27 11:36:50 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 10617823 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 3EF961759 for ; Thu, 27 Sep 2018 11:37:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 305D82B1D7 for ; Thu, 27 Sep 2018 11:37:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 24F102B208; Thu, 27 Sep 2018 11:37:14 +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 C4D902B1D7 for ; Thu, 27 Sep 2018 11:37:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727223AbeI0RzE (ORCPT ); Thu, 27 Sep 2018 13:55:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:37114 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727112AbeI0RzE (ORCPT ); Thu, 27 Sep 2018 13:55:04 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 04B54B12B; Thu, 27 Sep 2018 11:37:10 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id AEB381E3AA5; Thu, 27 Sep 2018 13:37:09 +0200 (CEST) From: Jan Kara To: Jens Axboe Cc: , Tetsuo Handa , Jan Kara Subject: [PATCH 12/14] loop: Move special partition reread handling in loop_clr_fd() Date: Thu, 27 Sep 2018 13:36:50 +0200 Message-Id: <20180927113652.5422-13-jack@suse.cz> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20180927113652.5422-1-jack@suse.cz> References: <20180927113652.5422-1-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 The call of __blkdev_reread_part() from loop_reread_partition() happens only when we need to invalidate partitions from loop_release(). Thus move a detection for this into loop_clr_fd() and simplify loop_reread_partition(). This makes loop_reread_partition() safe to use without loop_ctl_mutex because we use only lo->lo_number and lo->lo_file_name in case of error for reporting purposes (thus possibly reporting outdate information is not a big deal) and we are safe from 'lo' going away under us by elevated lo->lo_refcnt. Signed-off-by: Jan Kara --- drivers/block/loop.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index b4ea862f14fd..cce1a32ae6d0 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -631,18 +631,7 @@ static void loop_reread_partitions(struct loop_device *lo, { int rc; - /* - * bd_mutex has been held already in release path, so don't - * acquire it if this function is called in such case. - * - * If the reread partition isn't from release path, lo_refcnt - * must be at least one and it can only become zero when the - * current holder is released. - */ - if (!atomic_read(&lo->lo_refcnt)) - rc = __blkdev_reread_part(bdev); - else - rc = blkdev_reread_part(bdev); + rc = blkdev_reread_part(bdev); if (rc) pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", __func__, lo->lo_number, lo->lo_file_name, rc); @@ -1096,8 +1085,24 @@ static int __loop_clr_fd(struct loop_device *lo) module_put(THIS_MODULE); blk_mq_unfreeze_queue(lo->lo_queue); - if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) - loop_reread_partitions(lo, bdev); + if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) { + /* + * bd_mutex has been held already in release path, so don't + * acquire it if this function is called in such case. + * + * If the reread partition isn't from release path, lo_refcnt + * must be at least one and it can only become zero when the + * current holder is released. + */ + if (!atomic_read(&lo->lo_refcnt)) + err = __blkdev_reread_part(bdev); + else + err = blkdev_reread_part(bdev); + pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", + __func__, lo->lo_number, err); + /* Device is gone, no point in returning error */ + err = 0; + } lo->lo_flags = 0; if (!part_shift) lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;