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, URIBL_BLOCKED,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 16697C56202 for ; Fri, 20 Nov 2020 10:53:55 +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 2F20220657 for ; Fri, 20 Nov 2020 10:53:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F20220657 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz 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-361-ZC1mb4q0Nv2qLtV48uvcIg-1; Fri, 20 Nov 2020 05:53:48 -0500 X-MC-Unique: ZC1mb4q0Nv2qLtV48uvcIg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B60E7801B17; Fri, 20 Nov 2020 10:53:43 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 346E11002388; Fri, 20 Nov 2020 10:53:43 +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 48E834A7C6; Fri, 20 Nov 2020 10:53:42 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 0AKArbXP003128 for ; Fri, 20 Nov 2020 05:53:38 -0500 Received: by smtp.corp.redhat.com (Postfix) id 9E802115589D; Fri, 20 Nov 2020 10:53:37 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast01.extmail.prod.ext.rdu2.redhat.com [10.11.55.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9AA49115589B for ; Fri, 20 Nov 2020 10:53:24 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (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 69DD585829F for ; Fri, 20 Nov 2020 10:53:24 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-306-h7jR73IUMFO5D0PmrLFcQQ-1; Fri, 20 Nov 2020 05:53:21 -0500 X-MC-Unique: h7jR73IUMFO5D0PmrLFcQQ-1 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 015E9AED9; Fri, 20 Nov 2020 10:53:20 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id AC96F1E130B; Fri, 20 Nov 2020 11:53:19 +0100 (CET) Date: Fri, 20 Nov 2020 11:53:19 +0100 From: Jan Kara To: Christoph Hellwig Message-ID: <20201120105319.GA15537@quack2.suse.cz> References: <20201118084800.2339180-1-hch@lst.de> <20201118084800.2339180-16-hch@lst.de> <20201119143921.GX1981@quack2.suse.cz> <20201120091546.GE21715@lst.de> MIME-Version: 1.0 In-Reply-To: <20201120091546.GE21715@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) 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 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com Cc: Jens Axboe , Jan Kara , Mike Snitzer , Konrad Rzeszutek Wilk , Richard Weinberger , Josef Bacik , Coly Li , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, linux-mtd@lists.infradead.org, Jan Kara , Tejun Heo , xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mm@kvack.org Subject: Re: [dm-devel] [PATCH 15/20] block: merge struct block_device and struct hd_struct 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 2.84 on 10.5.11.22 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 Fri 20-11-20 10:15:46, Christoph Hellwig wrote: > On Thu, Nov 19, 2020 at 03:39:21PM +0100, Jan Kara wrote: > > This patch is kind of difficult to review due to the size of mostly > > mechanical changes mixed with not completely mechanical changes. Can we > > perhaps split out the mechanical bits? E.g. the rq->part => rq->bdev > > renaming is mechanical and notable part of the patch. Similarly the > > part->foo => part->bd_foo bits... > > We'd end with really weird patches that way. Never mind that I'm not > even sure how we could mechnically do the renaming. Well, I believe coccinelle should be able to do the renaming automatically. > > Also I'm kind of wondering: AFAIU the new lifetime rules, gendisk holds > > bdev reference and bdev is created on gendisk allocation so bdev lifetime is > > strictly larger than gendisk lifetime. But what now keeps bdev->bd_disk > > reference safe in presence device hot unplug? In most cases we are still > > protected by gendisk reference taken in __blkdev_get() but how about > > disk->lookup_sem and disk->flags dereferences before we actually grab the > > reference? > > Good question. I'll need to think about this a bit more. My thinking was that you could use kobject_get_unless_zero(bdev->bd_device->kobj) and after you hold this reference, you can do everything else safely. In this case it is really useful that device is embedded in block_dev and not in gendisk itself... Honza -- Jan Kara SUSE Labs, CR -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel