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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