From patchwork Wed Apr 22 09:56:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 227136 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 A5F7DC5518C for ; Wed, 22 Apr 2020 10:46:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84E6A20780 for ; Wed, 22 Apr 2020 10:46:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587552371; bh=+ikwfPbm7c6KxTJD0BmB89GFJ0B4TtDtOz7to9+x0x0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0VLZNRA5KI//zc1aQO/4yR5OvS2Hwnml+y+hqNx1Qw3jo9TLKMUYQnRlbk88LVjoO eVuk6H/o8GLeSC5ViO2vJSjacZnQq5IikQBYQDJrrssszak/PbqgfmrYPshJcaI3yQ gTRZlGDqzfxlWPebnCnnBjFtgGMIbpYvuY3AEXUc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729305AbgDVKRW (ORCPT ); Wed, 22 Apr 2020 06:17:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:53452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729309AbgDVKRU (ORCPT ); Wed, 22 Apr 2020 06:17:20 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 D18E02075A; Wed, 22 Apr 2020 10:17:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587550640; bh=+ikwfPbm7c6KxTJD0BmB89GFJ0B4TtDtOz7to9+x0x0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WLaP5fGTtujjMCWDcqVijEObMZZjO+D7j55Jii095M9REucI8MLXPWpxVf0FGos16 dNLEf8nqyZt+YN9HJ5CB1PwSDUAqoyn58qlW9CI5j5Tgt8v33J5hQD9a3qiY4ptzm4 E9KTPq6uwLjwlClTTgXJhv7IXl/3Eb3JAIprsVhs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ilya Dryomov , Jason Dillaman , Sasha Levin Subject: [PATCH 5.4 032/118] rbd: avoid a deadlock on header_rwsem when flushing notifies Date: Wed, 22 Apr 2020 11:56:33 +0200 Message-Id: <20200422095037.117674327@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095031.522502705@linuxfoundation.org> References: <20200422095031.522502705@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ilya Dryomov [ Upstream commit 0e4e1de5b63fa423b13593337a27fd2d2b0bcf77 ] rbd_unregister_watch() flushes notifies and therefore cannot be called under header_rwsem because a header update notify takes header_rwsem to synchronize with "rbd map". If mapping an image fails after the watch is established and a header update notify sneaks in, we deadlock when erroring out from rbd_dev_image_probe(). Move watch registration and unregistration out of the critical section. The only reason they were put there was to make header_rwsem management slightly more obvious. Fixes: 811c66887746 ("rbd: fix rbd map vs notify races") Signed-off-by: Ilya Dryomov Reviewed-by: Jason Dillaman Signed-off-by: Sasha Levin --- drivers/block/rbd.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index a67315786db47..bab9c546ba334 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -4636,6 +4636,10 @@ static void cancel_tasks_sync(struct rbd_device *rbd_dev) cancel_work_sync(&rbd_dev->unlock_work); } +/* + * header_rwsem must not be held to avoid a deadlock with + * rbd_dev_refresh() when flushing notifies. + */ static void rbd_unregister_watch(struct rbd_device *rbd_dev) { cancel_tasks_sync(rbd_dev); @@ -6942,6 +6946,9 @@ static void rbd_dev_image_release(struct rbd_device *rbd_dev) * device. If this image is the one being mapped (i.e., not a * parent), initiate a watch on its header object before using that * object to get detailed information about the rbd image. + * + * On success, returns with header_rwsem held for write if called + * with @depth == 0. */ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth) { @@ -6974,6 +6981,9 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth) } } + if (!depth) + down_write(&rbd_dev->header_rwsem); + ret = rbd_dev_header_info(rbd_dev); if (ret) goto err_out_watch; @@ -7027,6 +7037,8 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth) err_out_probe: rbd_dev_unprobe(rbd_dev); err_out_watch: + if (!depth) + up_write(&rbd_dev->header_rwsem); if (!depth) rbd_unregister_watch(rbd_dev); err_out_format: @@ -7085,12 +7097,9 @@ static ssize_t do_rbd_add(struct bus_type *bus, goto err_out_rbd_dev; } - down_write(&rbd_dev->header_rwsem); rc = rbd_dev_image_probe(rbd_dev, 0); - if (rc < 0) { - up_write(&rbd_dev->header_rwsem); + if (rc < 0) goto err_out_rbd_dev; - } /* If we are mapping a snapshot it must be marked read-only */ if (rbd_dev->spec->snap_id != CEPH_NOSNAP)