From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36054) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bkscC-0007sh-3J for qemu-devel@nongnu.org; Fri, 16 Sep 2016 08:51:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bkscB-0000SD-3u for qemu-devel@nongnu.org; Fri, 16 Sep 2016 08:51:36 -0400 Date: Fri, 16 Sep 2016 14:51:24 +0200 From: Kevin Wolf Message-ID: <20160916125124.GG4633@noname.redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v2 0/7] Add "read-only" to the options QDict List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alberto Garcia Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Am 15.09.2016 um 16:52 hat Alberto Garcia geschrieben: > This series adds "read-only" to the options QDict, fixing a > long-standing problem with the reopening code. > > [E] <- [D] <- [C] <- [B] <- [A] > > In a normal scenario, the active layer [A] is in read-write mode and > everything else is read-only. If we reopen [D] in read-write mode and > later reopen [B], then [D] will become read-only when inheriting the > flags from its parent (see bdrv_backing_options()). With this series, > inheriting options doesn't need to override values that have been > explicitly set before. > > The BDRV_O_RDWR flag is not removed yet, but its keep in sync with the > value of the "read-only" option. Removing the BDRV_O_RDWR flag is not > straightforward in all cases and can result in code that is > significantly slower and less readable. Therefore it will be dealt > with in the future. Thanks, applied to the block branch. Kevin