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/