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 X-Spam-Level: X-Spam-Status: No, score=-7.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 19060C71156 for ; Thu, 3 Dec 2020 06:41:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA9AC206E3 for ; Thu, 3 Dec 2020 06:41:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728599AbgLCGlf (ORCPT ); Thu, 3 Dec 2020 01:41:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58250 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727725AbgLCGle (ORCPT ); Thu, 3 Dec 2020 01:41:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606977608; 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=4a+ZpQmjLgoV6jCwYnyDxtAMBa2ORCm8AqUKIqPXkLU=; b=TNOg+tW5w6bLytas0nSPWClyY/6LwEw+YxX6eGXqK1YNB/lYtTWxP8JyD6ekoEQNi4WdG1 Ie0gvSaUGR/xLwQ1zAKeam+ud4/vOm20eDNF69VymJP2qPtWxdAKufh3FIgjPmmwFuRjND VDM37lko99uPbQRKRHXAMYdAKh7QprQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-95-jcc9ZzulNrKGkc15zcOW0Q-1; Thu, 03 Dec 2020 01:40:06 -0500 X-MC-Unique: jcc9ZzulNrKGkc15zcOW0Q-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BB5018030D5; Thu, 3 Dec 2020 06:40:04 +0000 (UTC) Received: from T590 (ovpn-13-173.pek2.redhat.com [10.72.13.173]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C920C1A890; Thu, 3 Dec 2020 06:39:51 +0000 (UTC) Date: Thu, 3 Dec 2020 14:39:41 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , Tejun Heo , Coly Li , Song Liu , dm-devel@redhat.com, linux-bcache@vger.kernel.org, linux-raid@vger.kernel.org, linux-s390@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCH 3/9] block: store a block_device pointer in struct bio Message-ID: <20201203063941.GA629758@T590> References: <20201201165424.2030647-1-hch@lst.de> <20201201165424.2030647-4-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201165424.2030647-4-hch@lst.de> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org On Tue, Dec 01, 2020 at 05:54:18PM +0100, Christoph Hellwig wrote: > Replace the gendisk pointer in struct bio with a pointer to the newly > improved struct block device. From that the gendisk can be trivially > accessed with an extra indirection, but it also allows to directly > look up all information related to partition remapping. The extra indirection is often done in fast path, so just wondering why you don't consider to embed gendisk into block_device? Then the extra indirection can be avoided. Thanks, Ming