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 DB8E1C2D0E4 for ; Fri, 27 Nov 2020 15:36:40 +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 10AD820795 for ; Fri, 27 Nov 2020 15:36:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 10AD820795 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-289-iCf249TZOXK3nd54HbU6Hg-1; Fri, 27 Nov 2020 10:36:36 -0500 X-MC-Unique: iCf249TZOXK3nd54HbU6Hg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 51C711007466; Fri, 27 Nov 2020 15:36:30 +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 B7EE65C1C2; Fri, 27 Nov 2020 15:36:29 +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 5C41C180954D; Fri, 27 Nov 2020 15:36:28 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 0ARFaQi1001729 for ; Fri, 27 Nov 2020 10:36:26 -0500 Received: by smtp.corp.redhat.com (Postfix) id 9C3642166B28; Fri, 27 Nov 2020 15:36:26 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast06.extmail.prod.ext.rdu2.redhat.com [10.11.55.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 967EA2166B2C for ; Fri, 27 Nov 2020 15:36:24 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) (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 56846186E122 for ; Fri, 27 Nov 2020 15:36:24 +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-416-mWXVcRtWOJ-K-yw1620wZg-1; Fri, 27 Nov 2020 10:36:20 -0500 X-MC-Unique: mWXVcRtWOJ-K-yw1620wZg-1 Received: by verein.lst.de (Postfix, from userid 2407) id 5CA0168B05; Fri, 27 Nov 2020 16:36:16 +0100 (CET) Date: Fri, 27 Nov 2020 16:36:15 +0100 From: Christoph Hellwig To: Jan Kara Message-ID: <20201127153615.GA7524@lst.de> References: <20201126130422.92945-1-hch@lst.de> <20201126130422.92945-38-hch@lst.de> <20201126182219.GC422@quack2.suse.cz> <20201127094842.GA15984@lst.de> <20201127124537.GC27162@quack2.suse.cz> MIME-Version: 1.0 In-Reply-To: <20201127124537.GC27162@quack2.suse.cz> 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 10.11.54.6 X-loop: dm-devel@redhat.com Cc: Jens Axboe , Chao Yu , Mike Snitzer , linux-mm@kvack.org, Greg Kroah-Hartman , Jan Kara , Josef Bacik , Coly Li , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, linux-mtd@lists.infradead.org, Johannes Thumshirn , Tejun Heo , linux-bcache@vger.kernel.org, Christoph Hellwig Subject: Re: [dm-devel] [PATCH 37/44] block: switch partition lookup to use struct block_device 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 10.5.11.16 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, Nov 27, 2020 at 01:45:37PM +0100, Jan Kara wrote: > > At this point the hd_struct is already allocated together with the > > block_device, and thus only freed after the last block_device reference > > goes away plus the inode freeing RCU grace period. So the device model > > ref to part is indeed gone, but that simply does not matter any more. > > Well, but once device model ref to part is gone, we're going to free the > bdev inode ref as well. Thus there's nothing which pins the bdev containing > hd_struct? > > But now as I'm thinking about it you later switch the device model reference > to just pure inode reference and use igrab() which will reliably return > NULL if the inode is on it's way to be destroyed so probably we are safe in > the final state. igrab always succeeds. But we should switch to a tryget. -- 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 D962AC63798 for ; Fri, 27 Nov 2020 15:36:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9DF2120B80 for ; Fri, 27 Nov 2020 15:36:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730537AbgK0PgV (ORCPT ); Fri, 27 Nov 2020 10:36:21 -0500 Received: from verein.lst.de ([213.95.11.211]:37927 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730487AbgK0PgV (ORCPT ); Fri, 27 Nov 2020 10:36:21 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 5CA0168B05; Fri, 27 Nov 2020 16:36:16 +0100 (CET) Date: Fri, 27 Nov 2020 16:36:15 +0100 From: Christoph Hellwig To: Jan Kara Cc: Christoph Hellwig , Jens Axboe , Tejun Heo , Josef Bacik , Coly Li , Mike Snitzer , Greg Kroah-Hartman , Johannes Thumshirn , dm-devel@redhat.com, Jan Kara , linux-block@vger.kernel.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Chao Yu Subject: Re: [PATCH 37/44] block: switch partition lookup to use struct block_device Message-ID: <20201127153615.GA7524@lst.de> References: <20201126130422.92945-1-hch@lst.de> <20201126130422.92945-38-hch@lst.de> <20201126182219.GC422@quack2.suse.cz> <20201127094842.GA15984@lst.de> <20201127124537.GC27162@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201127124537.GC27162@quack2.suse.cz> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org On Fri, Nov 27, 2020 at 01:45:37PM +0100, Jan Kara wrote: > > At this point the hd_struct is already allocated together with the > > block_device, and thus only freed after the last block_device reference > > goes away plus the inode freeing RCU grace period. So the device model > > ref to part is indeed gone, but that simply does not matter any more. > > Well, but once device model ref to part is gone, we're going to free the > bdev inode ref as well. Thus there's nothing which pins the bdev containing > hd_struct? > > But now as I'm thinking about it you later switch the device model reference > to just pure inode reference and use igrab() which will reliably return > NULL if the inode is on it's way to be destroyed so probably we are safe in > the final state. igrab always succeeds. But we should switch to a tryget. 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 ABE35C2D0E4 for ; Fri, 27 Nov 2020 15:36:53 +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 385BB20795 for ; Fri, 27 Nov 2020 15:36:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="z15jaNNv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 385BB20795 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=YB9MzUV2ChwuOeMIeo847VI7kZA+PdkC/6j4G0msQmc=; b=z15jaNNvce0+9udeSk5ocQSRQ ZRDzLMf066W4Tad8MCEhju6Qh7uC87Q0NVVUWW2rev9x77usTmw1EymIkUXtAM7oJpjpm9XwnR5AK 85FNqn9pD35uloD4qaN/IA24//Xs8JkO4d3lVui1Xk1k3onUVtwhm8VL67XZvnQnmyohiNhjHTeeX ASAJIWeP+xpFNRuRnzWHY3bn3MXyPZs1lkyicSeajklFn+jijEOpT3UllAyYnI7Zq54Mpa1K2joCc yMNyvejSuBWUW5A2Gnao7ZqeGBfQIK24fbNjlWJkTslONZFJlOC1UZKR6leUkW+AOtDVinJe4qpyc GFHlpT7Cw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kifnK-00034f-8l; Fri, 27 Nov 2020 15:36:22 +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 1kifnI-00034J-9j for linux-mtd@lists.infradead.org; Fri, 27 Nov 2020 15:36:20 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 5CA0168B05; Fri, 27 Nov 2020 16:36:16 +0100 (CET) Date: Fri, 27 Nov 2020 16:36:15 +0100 From: Christoph Hellwig To: Jan Kara Subject: Re: [PATCH 37/44] block: switch partition lookup to use struct block_device Message-ID: <20201127153615.GA7524@lst.de> References: <20201126130422.92945-1-hch@lst.de> <20201126130422.92945-38-hch@lst.de> <20201126182219.GC422@quack2.suse.cz> <20201127094842.GA15984@lst.de> <20201127124537.GC27162@quack2.suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201127124537.GC27162@quack2.suse.cz> 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-20201127_103620_478550_3739FF5D X-CRM114-Status: GOOD ( 14.81 ) 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 , Chao Yu , Mike Snitzer , linux-mm@kvack.org, Greg Kroah-Hartman , Jan Kara , Josef Bacik , Coly Li , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, linux-mtd@lists.infradead.org, Johannes Thumshirn , Tejun Heo , 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 Fri, Nov 27, 2020 at 01:45:37PM +0100, Jan Kara wrote: > > At this point the hd_struct is already allocated together with the > > block_device, and thus only freed after the last block_device reference > > goes away plus the inode freeing RCU grace period. So the device model > > ref to part is indeed gone, but that simply does not matter any more. > > Well, but once device model ref to part is gone, we're going to free the > bdev inode ref as well. Thus there's nothing which pins the bdev containing > hd_struct? > > But now as I'm thinking about it you later switch the device model reference > to just pure inode reference and use igrab() which will reliably return > NULL if the inode is on it's way to be destroyed so probably we are safe in > the final state. igrab always succeeds. But we should switch to a tryget. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/