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 E65C9C63777 for ; Thu, 3 Dec 2020 07:12:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 912E620BED for ; Thu, 3 Dec 2020 07:12:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387409AbgLCHMk (ORCPT ); Thu, 3 Dec 2020 02:12:40 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:57719 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729780AbgLCHMj (ORCPT ); Thu, 3 Dec 2020 02:12:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606979473; 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=nXF3TZzoNrGr5gKvXhDZQd3WblgUNL7SVEFeVZVdFmc=; b=WJ2HpcR+rN0ADxJnSendrP5ZJMXYCz3LImdR5I6QJSeBVdLUUccE7G33m2lXSAp1X4wQqp lhmzkFtkUh88LDUIwQ8EFWwn7e0K6t7BoWNNTsdPsGu11Ud76GZkTkZODO4loKXhfBev/O AcotYzMVK1OGMClbukUMr5M2AIK3v8U= 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-446-W-Pz2EQHPWyTIzTKtgFMxw-1; Thu, 03 Dec 2020 02:11:11 -0500 X-MC-Unique: W-Pz2EQHPWyTIzTKtgFMxw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ECA8F8042B5; Thu, 3 Dec 2020 07:11:09 +0000 (UTC) Received: from T590 (ovpn-13-173.pek2.redhat.com [10.72.13.173]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DEEDD60BF1; Thu, 3 Dec 2020 07:10:59 +0000 (UTC) Date: Thu, 3 Dec 2020 15:10:55 +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: <20201203071055.GA633702@T590> References: <20201201165424.2030647-1-hch@lst.de> <20201201165424.2030647-4-hch@lst.de> <20201203063941.GA629758@T590> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201203063941.GA629758@T590> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On Thu, Dec 03, 2020 at 02:40:04PM +0800, Ming Lei wrote: > 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. oops, that is only possible for disk, and indirection is still needed for partitions. Thanks, Ming