From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52628) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fchmo-0005vE-Dz for qemu-devel@nongnu.org; Mon, 09 Jul 2018 21:49:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fchmn-0006ZL-K5 for qemu-devel@nongnu.org; Mon, 09 Jul 2018 21:49:50 -0400 Date: Tue, 10 Jul 2018 09:49:35 +0800 From: Fam Zheng Message-ID: <20180710014935.GF17581@lemon.usersys.redhat.com> References: <20180709163719.87107-1-vsementsov@virtuozzo.com> <20180709163719.87107-2-vsementsov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180709163719.87107-2-vsementsov@virtuozzo.com> Subject: Re: [Qemu-devel] [PATCH v5 1/4] block/io: fix copy_range List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, pl@kamp.de, pbonzini@redhat.com, ronniesahlberg@gmail.com, stefanha@redhat.com, mreitz@redhat.com, kwolf@redhat.com, jcody@redhat.com, jsnow@redhat.com, den@openvz.org On Mon, 07/09 19:37, Vladimir Sementsov-Ogievskiy wrote: > Here two things are fixed: > > 1. Architecture > > On each recursion step, we go to the child of src or dst, only for one > of them. So, it's wrong to create tracked requests for both on each > step. It leads to tracked requests duplication. > > 2. Wait for serializing requests on write path independently of > BDRV_REQ_NO_SERIALISING > > Before commit 9ded4a01149 "backup: Use copy offloading", > BDRV_REQ_NO_SERIALISING was used for only one case: read in > copy-on-write operation during backup. Also, the flag was handled only > on read path (in bdrv_co_preadv and bdrv_aligned_preadv). > > After 9ded4a01149, flag is used for not waiting serializing operations > on backup target (in same case of copy-on-write operation). This > behavior change is unsubstantiated and potentially dangerous, let's > drop it and add additional asserts and documentation. > > Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Fam Zheng