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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 77F66C63777 for ; Thu, 3 Dec 2020 08:31:46 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5B3B021527 for ; Thu, 3 Dec 2020 08:31:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B3B021527 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com 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-475-Qe-Vz6UkPvqLh4qcHrV4bg-1; Thu, 03 Dec 2020 03:31:39 -0500 X-MC-Unique: Qe-Vz6UkPvqLh4qcHrV4bg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 422E3107ACF8; Thu, 3 Dec 2020 08:31:34 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F0A8D5D9CA; Thu, 3 Dec 2020 08:31:33 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 3618E180954D; Thu, 3 Dec 2020 08:31:33 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 0B38U2OM007950 for ; Thu, 3 Dec 2020 03:30:02 -0500 Received: by smtp.corp.redhat.com (Postfix) id 1376DD7DEC; Thu, 3 Dec 2020 08:30:02 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast04.extmail.prod.ext.rdu2.redhat.com [10.11.55.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0E1F2D7DF3 for ; Thu, 3 Dec 2020 08:29:58 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-1.mimecast.com [207.211.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D14E4108C0ED for ; Thu, 3 Dec 2020 08:29:58 +0000 (UTC) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-579-YV26tvZzMECdWjyLL2fY3A-1; Thu, 03 Dec 2020 03:29:54 -0500 X-MC-Unique: YV26tvZzMECdWjyLL2fY3A-1 Received: by verein.lst.de (Postfix, from userid 2407) id 8169467373; Thu, 3 Dec 2020 09:29:51 +0100 (CET) Date: Thu, 3 Dec 2020 09:29:51 +0100 From: Christoph Hellwig To: Ming Lei Message-ID: <20201203082951.GA15581@lst.de> References: <20201201165424.2030647-1-hch@lst.de> <20201201165424.2030647-4-hch@lst.de> <20201203063941.GA629758@T590> <20201203071055.GA633702@T590> MIME-Version: 1.0 In-Reply-To: <20201203071055.GA633702@T590> User-Agent: Mutt/1.5.17 (2007-11-01) X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-loop: dm-devel@redhat.com Cc: Jens Axboe , linux-s390@vger.kernel.org, linux-bcache@vger.kernel.org, Coly Li , linux-raid@vger.kernel.org, Song Liu , dm-devel@redhat.com, linux-block@vger.kernel.org, Tejun Heo , Christoph Hellwig Subject: Re: [dm-devel] [PATCH 3/9] block: store a block_device pointer in struct bio X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Dec 03, 2020 at 03:10:55PM +0800, Ming Lei wrote: > 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. I looked into that, but given that the block device is allocated as part of the inode we'd need to tell ->alloc_inode if we want to allocate the small inode without the gendisk, or the large one with it which doesn't work with the current interface. Beause the hd_struct is gone we're still not using more structures in the I/O path than we did before. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel 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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 92459C64E7B for ; Thu, 3 Dec 2020 08:30:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30D8B217A0 for ; Thu, 3 Dec 2020 08:30:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388410AbgLCIag (ORCPT ); Thu, 3 Dec 2020 03:30:36 -0500 Received: from verein.lst.de ([213.95.11.211]:57585 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388390AbgLCIaf (ORCPT ); Thu, 3 Dec 2020 03:30:35 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 8169467373; Thu, 3 Dec 2020 09:29:51 +0100 (CET) Date: Thu, 3 Dec 2020 09:29:51 +0100 From: Christoph Hellwig To: Ming Lei Cc: Christoph Hellwig , 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: <20201203082951.GA15581@lst.de> References: <20201201165424.2030647-1-hch@lst.de> <20201201165424.2030647-4-hch@lst.de> <20201203063941.GA629758@T590> <20201203071055.GA633702@T590> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201203071055.GA633702@T590> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org On Thu, Dec 03, 2020 at 03:10:55PM +0800, Ming Lei wrote: > 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. I looked into that, but given that the block device is allocated as part of the inode we'd need to tell ->alloc_inode if we want to allocate the small inode without the gendisk, or the large one with it which doesn't work with the current interface. Beause the hd_struct is gone we're still not using more structures in the I/O path than we did before.