From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50669) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eopy9-0000bL-MX for qemu-devel@nongnu.org; Thu, 22 Feb 2018 07:27:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eopy8-00064O-Qu for qemu-devel@nongnu.org; Thu, 22 Feb 2018 07:27:25 -0500 Date: Thu, 22 Feb 2018 13:27:00 +0100 From: Kevin Wolf Message-ID: <20180222122700.GE4147@localhost.localdomain> References: <20180205151835.20812-1-mreitz@redhat.com> <20180205151835.20812-2-mreitz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180205151835.20812-2-mreitz@redhat.com> Subject: Re: [Qemu-devel] [PATCH v8 01/26] block/mirror: Small absolute-paths simplification List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, Alberto Garcia Am 05.02.2018 um 16:18 hat Max Reitz geschrieben: > When invoking drive-mirror in absolute-paths mode, the target's backing > BDS is assigned to it in mirror_exit(). The current logic only does so > if the target does not have that backing BDS already; but it actually > cannot have a backing BDS at all (the BDS is opened with O_NO_BACKING in > qmp_drive_mirror()), so just assert that and assign the new backing BDS > unconditionally. > > Signed-off-by: Max Reitz > Reviewed-by: Alberto Garcia Introducing new assumptions that the graph stays unmodified between the start of a block job and its completion feels a bit adventurous when all of the blockdev work is moving towards making things more flexible. If we really do want to enforce this, I guess you finally found a use case for BLK_PERM_GRAPH_MOD. Kevin