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 8D843C56202 for ; Thu, 26 Nov 2020 08:20:28 +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 BFC6420872 for ; Thu, 26 Nov 2020 08:20:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFC6420872 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-505-iaQNCOUDMimdPZjKxx94wA-1; Thu, 26 Nov 2020 03:20:23 -0500 X-MC-Unique: iaQNCOUDMimdPZjKxx94wA-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 AD79681CBDB; Thu, 26 Nov 2020 08:20:17 +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 0212A5D9C6; Thu, 26 Nov 2020 08:20:16 +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 A59E34BB40; Thu, 26 Nov 2020 08:20:10 +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 0AQ8H07k005652 for ; Thu, 26 Nov 2020 03:17:00 -0500 Received: by smtp.corp.redhat.com (Postfix) id 4B4BA1009A04; Thu, 26 Nov 2020 08:17:00 +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 479E91008B7C for ; Thu, 26 Nov 2020 08:16:57 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (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 1EBFC858EEC for ; Thu, 26 Nov 2020 08:16:57 +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-361-S8t3p4OiPxi3naQRrrUZfQ-1; Thu, 26 Nov 2020 03:16:54 -0500 X-MC-Unique: S8t3p4OiPxi3naQRrrUZfQ-1 Received: by verein.lst.de (Postfix, from userid 2407) id AF45968B02; Thu, 26 Nov 2020 09:16:50 +0100 (CET) Date: Thu, 26 Nov 2020 09:16:50 +0100 From: Christoph Hellwig To: Tejun Heo Message-ID: <20201126081650.GA18807@lst.de> References: <20201124132751.3747337-1-hch@lst.de> <20201124132751.3747337-26-hch@lst.de> <20201125164515.GB1975@lst.de> MIME-Version: 1.0 In-Reply-To: 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 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com Cc: Jens Axboe , Jan Kara , Mike Snitzer , Konrad Rzeszutek Wilk , Greg Kroah-Hartman , Jan Kara , Josef Bacik , Coly Li , linux-block@vger.kernel.org, Richard Weinberger , dm-devel@redhat.com, linux-mtd@lists.infradead.org, linux-mm@kvack.org, Johannes Thumshirn , linux-fsdevel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, Christoph Hellwig Subject: Re: [dm-devel] [PATCH 25/45] block: reference struct block_device from 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 2.79 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 Wed, Nov 25, 2020 at 03:20:23PM -0500, Tejun Heo wrote: > Agreed. It'd be nice to replace the stale comment. I've updated the comment. > > Jan added lookup_sem in commit 56c0908c855afbb to prevent a three way > > race between del_gendisk and blkdev_open due to the weird bdev vs > > gendisk lifetime rules. None of that can happen with the new lookup > > scheme. > > Understood. I think it'd be worthwhile to note that in the commit log. So after the idea of just holding a disk reference from each bdev did not work out very well I've reworked this a bit, and lookup_sem stays, but becomes global to protect the disk lookup (similar to the previous global bdev_map_lock). -- 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 203E8C64E75 for ; Thu, 26 Nov 2020 08:17:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF9C620DD4 for ; Thu, 26 Nov 2020 08:17:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388782AbgKZIQy (ORCPT ); Thu, 26 Nov 2020 03:16:54 -0500 Received: from verein.lst.de ([213.95.11.211]:33418 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388774AbgKZIQy (ORCPT ); Thu, 26 Nov 2020 03:16:54 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id AF45968B02; Thu, 26 Nov 2020 09:16:50 +0100 (CET) Date: Thu, 26 Nov 2020 09:16:50 +0100 From: Christoph Hellwig To: Tejun Heo Cc: Christoph Hellwig , Jens Axboe , Josef Bacik , Konrad Rzeszutek Wilk , Coly Li , Mike Snitzer , Greg Kroah-Hartman , Jan Kara , Johannes Thumshirn , dm-devel@redhat.com, Richard Weinberger , Jan Kara , linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 25/45] block: reference struct block_device from struct hd_struct Message-ID: <20201126081650.GA18807@lst.de> References: <20201124132751.3747337-1-hch@lst.de> <20201124132751.3747337-26-hch@lst.de> <20201125164515.GB1975@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org On Wed, Nov 25, 2020 at 03:20:23PM -0500, Tejun Heo wrote: > Agreed. It'd be nice to replace the stale comment. I've updated the comment. > > Jan added lookup_sem in commit 56c0908c855afbb to prevent a three way > > race between del_gendisk and blkdev_open due to the weird bdev vs > > gendisk lifetime rules. None of that can happen with the new lookup > > scheme. > > Understood. I think it'd be worthwhile to note that in the commit log. So after the idea of just holding a disk reference from each bdev did not work out very well I've reworked this a bit, and lookup_sem stays, but becomes global to protect the disk lookup (similar to the previous global bdev_map_lock). 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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 7CFC1C63777 for ; Thu, 26 Nov 2020 08:18:20 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C6C3820872 for ; Thu, 26 Nov 2020 08:18:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="l9vHB9bN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C6C3820872 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=nKQHVh90sOruw5wFaxAItyZ8r9c935GZpNjTANxr5YM=; b=l9vHB9bN3c19EwVA8SyvLitOk CpiPxu2UydfuDdEOwxm1+Dq9I3CxbsuckbUOHopKWpyhBVatq59FjuQxyFGtobDIEyAd8z/30i+Qq weHNQYGHjmNQQsP7JDpEJjW4ymAJfCPxwOaZS+qKYC7Wo9DWzLSQZBxtx8rluSNfiYDley/j5pj1G 2xsSGoG9W13Lg67ntFbbfEkW2+hGbfqrQJcX1B2yI63L+VcGpi7mXick73Uhb1706oYYkZ57MQ3An /8FEyaC1mIE5w5jXRJLd6VjLJNdGLDAIIx/eBtGwAVBkqx5va87bgaVphHKaMARkVFCsq2LNzoZiZ gW2h4V6rQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kiCSZ-0007fj-N2; Thu, 26 Nov 2020 08:16:59 +0000 Received: from verein.lst.de ([213.95.11.211]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kiCSU-0007es-G6 for linux-mtd@lists.infradead.org; Thu, 26 Nov 2020 08:16:58 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id AF45968B02; Thu, 26 Nov 2020 09:16:50 +0100 (CET) Date: Thu, 26 Nov 2020 09:16:50 +0100 From: Christoph Hellwig To: Tejun Heo Subject: Re: [PATCH 25/45] block: reference struct block_device from struct hd_struct Message-ID: <20201126081650.GA18807@lst.de> References: <20201124132751.3747337-1-hch@lst.de> <20201124132751.3747337-26-hch@lst.de> <20201125164515.GB1975@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201126_031657_837901_B3729D07 X-CRM114-Status: GOOD ( 13.20 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , Jan Kara , Mike Snitzer , Konrad Rzeszutek Wilk , Greg Kroah-Hartman , Jan Kara , Josef Bacik , Coly Li , linux-block@vger.kernel.org, Richard Weinberger , dm-devel@redhat.com, linux-mtd@lists.infradead.org, linux-mm@kvack.org, Johannes Thumshirn , linux-fsdevel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Wed, Nov 25, 2020 at 03:20:23PM -0500, Tejun Heo wrote: > Agreed. It'd be nice to replace the stale comment. I've updated the comment. > > Jan added lookup_sem in commit 56c0908c855afbb to prevent a three way > > race between del_gendisk and blkdev_open due to the weird bdev vs > > gendisk lifetime rules. None of that can happen with the new lookup > > scheme. > > Understood. I think it'd be worthwhile to note that in the commit log. So after the idea of just holding a disk reference from each bdev did not work out very well I've reworked this a bit, and lookup_sem stays, but becomes global to protect the disk lookup (similar to the previous global bdev_map_lock). ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/