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 64841E95A96 for ; Mon, 9 Oct 2023 13:19:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376783AbjJINTM (ORCPT ); Mon, 9 Oct 2023 09:19:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377038AbjJINSx (ORCPT ); Mon, 9 Oct 2023 09:18:53 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D075D99 for ; Mon, 9 Oct 2023 06:18:51 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18974C433C8; Mon, 9 Oct 2023 13:18:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696857531; bh=58jHYPSN9dVun7UF0ALfz+oo8ZZv3A3bviJTsizXR+A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kvZyxbLR8fYiV1nVD9jEnd0Aoetqe3RloBcYhumQv8ZzNCq9/JEl2+Fs65kRG9M/L w2THUg/FYXzzUEcDzDX5rBtRc2pcF3brJg5hyu6VxsBnKbhG4CfKaWD80jwSh6JeOb UEiUA3DxWjTaIAsvHYtvc32YQ8wauQtwovkmLeCA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ilya Dryomov , Dongsheng Yang , Sasha Levin Subject: [PATCH 6.1 049/162] rbd: take header_rwsem in rbd_dev_refresh() only when updating Date: Mon, 9 Oct 2023 15:00:30 +0200 Message-ID: <20231009130124.293492792@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231009130122.946357448@linuxfoundation.org> References: <20231009130122.946357448@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ilya Dryomov commit 0b207d02bd9ab8dcc31b262ca9f60dbc1822500d upstream. rbd_dev_refresh() has been holding header_rwsem across header and parent info read-in unnecessarily for ages. With commit 870611e4877e ("rbd: get snapshot context after exclusive lock is ensured to be held"), the potential for deadlocks became much more real owning to a) header_rwsem now nesting inside lock_rwsem and b) rw_semaphores not allowing new readers after a writer is registered. For example, assuming that I/O request 1, I/O request 2 and header read-in request all target the same OSD: 1. I/O request 1 comes in and gets submitted 2. watch error occurs 3. rbd_watch_errcb() takes lock_rwsem for write, clears owner_cid and releases lock_rwsem 4. after reestablishing the watch, rbd_reregister_watch() calls rbd_dev_refresh() which takes header_rwsem for write and submits a header read-in request 5. I/O request 2 comes in: after taking lock_rwsem for read in __rbd_img_handle_request(), it blocks trying to take header_rwsem for read in rbd_img_object_requests() 6. another watch error occurs 7. rbd_watch_errcb() blocks trying to take lock_rwsem for write 8. I/O request 1 completion is received by the messenger but can't be processed because lock_rwsem won't be granted anymore 9. header read-in request completion can't be received, let alone processed, because the messenger is stranded Change rbd_dev_refresh() to take header_rwsem only for actually updating rbd_dev->header. Header and parent info read-in don't need any locking. Cc: stable@vger.kernel.org # 0b035401c570: rbd: move rbd_dev_refresh() definition Cc: stable@vger.kernel.org # 510a7330c82a: rbd: decouple header read-in from updating rbd_dev->header Cc: stable@vger.kernel.org # c10311776f0a: rbd: decouple parent info read-in from updating rbd_dev Cc: stable@vger.kernel.org Fixes: 870611e4877e ("rbd: get snapshot context after exclusive lock is ensured to be held") Signed-off-by: Ilya Dryomov Reviewed-by: Dongsheng Yang Signed-off-by: Sasha Levin --- drivers/block/rbd.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 38c92b1b03466..afc92869cba42 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -6987,7 +6987,14 @@ static void rbd_dev_update_header(struct rbd_device *rbd_dev, rbd_assert(rbd_image_format_valid(rbd_dev->image_format)); rbd_assert(rbd_dev->header.object_prefix); /* !first_time */ - rbd_dev->header.image_size = header->image_size; + if (rbd_dev->header.image_size != header->image_size) { + rbd_dev->header.image_size = header->image_size; + + if (!rbd_is_snap(rbd_dev)) { + rbd_dev->mapping.size = header->image_size; + rbd_dev_update_size(rbd_dev); + } + } ceph_put_snap_context(rbd_dev->header.snapc); rbd_dev->header.snapc = header->snapc; @@ -7045,11 +7052,9 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev) { struct rbd_image_header header = { 0 }; struct parent_image_info pii = { 0 }; - u64 mapping_size; int ret; - down_write(&rbd_dev->header_rwsem); - mapping_size = rbd_dev->mapping.size; + dout("%s rbd_dev %p\n", __func__, rbd_dev); ret = rbd_dev_header_info(rbd_dev, &header, false); if (ret) @@ -7065,18 +7070,13 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev) goto out; } + down_write(&rbd_dev->header_rwsem); rbd_dev_update_header(rbd_dev, &header); if (rbd_dev->parent) rbd_dev_update_parent(rbd_dev, &pii); - - rbd_assert(!rbd_is_snap(rbd_dev)); - rbd_dev->mapping.size = rbd_dev->header.image_size; - -out: up_write(&rbd_dev->header_rwsem); - if (!ret && mapping_size != rbd_dev->mapping.size) - rbd_dev_update_size(rbd_dev); +out: rbd_parent_info_cleanup(&pii); rbd_image_header_cleanup(&header); return ret; -- 2.40.1