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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B462C433EF for ; Mon, 27 Jun 2022 11:38:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236388AbiF0LhS (ORCPT ); Mon, 27 Jun 2022 07:37:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236295AbiF0Lg3 (ORCPT ); Mon, 27 Jun 2022 07:36:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76131E58; Mon, 27 Jun 2022 04:32:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 23DE4B81122; Mon, 27 Jun 2022 11:32:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BDCDC3411D; Mon, 27 Jun 2022 11:31:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656329518; bh=z+1DQVTPAggy8DmvFiwP/5SP/t/XK2yDDfu1fqt3xws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=abqLj6Q/miXmci2flJaoCiW49nD0L+2T7fplpX79soYfQa8C6j2v8oywCjVJ9VTTc 2Pks3TN62LSnzsG1PkfXgahpFJB1FHtzKqGWHMQX0Md+Dfb+JJOwRolwaFnAt6kqqL wsLgGJaK710fie/nvlIaKYBN0klr/5BS7n86EEKc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikos Tsironis , Mike Snitzer Subject: [PATCH 5.15 025/135] dm era: commit metadata in postsuspend after worker stops Date: Mon, 27 Jun 2022 13:20:32 +0200 Message-Id: <20220627111938.890650023@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220627111938.151743692@linuxfoundation.org> References: <20220627111938.151743692@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nikos Tsironis commit 9ae6e8b1c9bbf6874163d1243e393137313762b7 upstream. During postsuspend dm-era does the following: 1. Archives the current era 2. Commits the metadata, as part of the RPC call for archiving the current era 3. Stops the worker Until the worker stops, it might write to the metadata again. Moreover, these writes are not flushed to disk immediately, but are cached by the dm-bufio client, which writes them back asynchronously. As a result, the committed metadata of a suspended dm-era device might not be consistent with the in-core metadata. In some cases, this can result in the corruption of the on-disk metadata. Suppose the following sequence of events: 1. Load a new table, e.g. a snapshot-origin table, to a device with a dm-era table 2. Suspend the device 3. dm-era commits its metadata, but the worker does a few more metadata writes until it stops, as part of digesting an archived writeset 4. These writes are cached by the dm-bufio client 5. Load the dm-era table to another device. 6. The new instance of the dm-era target loads the committed, on-disk metadata, which don't include the extra writes done by the worker after the metadata commit. 7. Resume the new device 8. The new dm-era target instance starts using the metadata 9. Resume the original device 10. The destructor of the old dm-era target instance is called and destroys the dm-bufio client, which results in flushing the cached writes to disk 11. These writes might overwrite the writes done by the new dm-era instance, hence corrupting its metadata. Fix this by committing the metadata after the worker stops running. stop_worker uses flush_workqueue to flush the current work. However, the work item may re-queue itself and flush_workqueue doesn't wait for re-queued works to finish. This could result in the worker changing the metadata after they have been committed, or writing to the metadata concurrently with the commit in the postsuspend thread. Use drain_workqueue instead, which waits until the work and all re-queued works finish. Fixes: eec40579d8487 ("dm: add era target") Cc: stable@vger.kernel.org # v3.15+ Signed-off-by: Nikos Tsironis Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-era-target.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/md/dm-era-target.c +++ b/drivers/md/dm-era-target.c @@ -1400,7 +1400,7 @@ static void start_worker(struct era *era static void stop_worker(struct era *era) { atomic_set(&era->suspended, 1); - flush_workqueue(era->wq); + drain_workqueue(era->wq); } /*---------------------------------------------------------------- @@ -1570,6 +1570,12 @@ static void era_postsuspend(struct dm_ta } stop_worker(era); + + r = metadata_commit(era->md); + if (r) { + DMERR("%s: metadata_commit failed", __func__); + /* FIXME: fail mode */ + } } static int era_preresume(struct dm_target *ti)