From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F7CD8F41 for ; Wed, 18 Oct 2023 02:36:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LROMdUnp" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01544AB for ; Tue, 17 Oct 2023 19:36:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1697596607; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=RV682s6nNPGRHlqZgk5Xv8DjWX7mCN9z9Iln0uNl9DY=; b=LROMdUnp1FHWYjZzlWA0LfiXMesrpiN1V5YH0HIRTrN1dpceXqkeT64CyP7/hlQ+wm3YyO i2/hveorgn9ENMae1r/6uGzi0D2HasE0B7Ltz45kYVB2/3tM5EY75Sb2S8TYgDs5wSjMc2 0YsH92POYXwiESVCdt10OvYN+V66veE= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-378-pD8srjfNMri8P_deMHG4-w-1; Tue, 17 Oct 2023 22:36:45 -0400 X-MC-Unique: pD8srjfNMri8P_deMHG4-w-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BA07229AB3F7; Wed, 18 Oct 2023 02:36:44 +0000 (UTC) Received: from fedora (unknown [10.72.120.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DFAF4492BFA; Wed, 18 Oct 2023 02:36:39 +0000 (UTC) Date: Wed, 18 Oct 2023 10:36:34 +0800 From: Ming Lei To: Christoph Hellwig Cc: Christian Brauner , Al Viro , Jens Axboe , Jan Kara , Denis Efremov , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 2/5] block: WARN_ON_ONCE() when we remove active partitions Message-ID: References: <20231017184823.1383356-1-hch@lst.de> <20231017184823.1383356-3-hch@lst.de> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231017184823.1383356-3-hch@lst.de> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL, SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, Oct 17, 2023 at 08:48:20PM +0200, Christoph Hellwig wrote: > From: Christian Brauner > > The logic for disk->open_partitions is: > > blkdev_get_by_*() > -> bdev_is_partition() > -> blkdev_get_part() > -> blkdev_get_whole() // bdev_whole->bd_openers++ > -> if (part->bd_openers == 0) > disk->open_partitions++ > part->bd_openers > > In other words, when we first claim/open a partition we increment > disk->open_partitions and only when all part->bd_openers are closed will > disk->open_partitions be zero. That should mean that > disk->open_partitions is always > 0 as long as there's anyone that > has an open partition. > > So the check for disk->open_partitions should meand that we can never > remove an active partition that has a holder and holder ops set. Assert > that in the code. The main disk isn't removed so that check doesn't work > for disk->part0 which is what we want. After all we only care about > partition not about the main disk. > > Signed-off-by: Christian Brauner inc/dec(part->bd_openers) is always done with ->open_mutex held, so this change is correct. Reviewed-by: Ming Lei Thanks, Ming