From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44476) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cEy6C-0005zu-Pv for qemu-devel@nongnu.org; Thu, 08 Dec 2016 07:46:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cEy6C-0003GR-0O for qemu-devel@nongnu.org; Thu, 08 Dec 2016 07:46:56 -0500 From: Markus Armbruster References: <87oa0q1t21.fsf@dusky.pond.sub.org> <20161207025457.GB30227@lemon> <20161207094832.GA4773@noname.str.redhat.com> <20161207100339.GB2286@lemon> Date: Thu, 08 Dec 2016 13:46:47 +0100 In-Reply-To: <20161207100339.GB2286@lemon> (Fam Zheng's message of "Wed, 7 Dec 2016 18:03:39 +0800") Message-ID: <87shpybnbc.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [Qemu-block] Meeting notes on -blockdev, dynamic backend reconfiguration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: Kevin Wolf , qemu-block@nongnu.org, qemu-devel@nongnu.org Fam Zheng writes: > On Wed, 12/07 10:48, Kevin Wolf wrote: >> > If so I think there is no race to worry about, mirror-filter should go >> > away only after a QMP command. >> >> Currently, a mirror job goes away whenever it is done. This is not >> directly tied to a QMP command. > > Ah right, block-job-complete is only "start to complete" and the job goes away > at some later point. I thought this is "the" QMP command but it is not. > >> >> Of course, in the new job API we want an explicit job-delete, so in >> that case it wouldn't happen, but we need to keep the old case for >> compatibility. > > Another possibility is to add a placeholder node in the right location first > then fill in the actual throttling node once created. QMP owns the placeholder > node so it won't suddenly vanish when mirror job goes away. I'm not sure I understand this idea. Could you explain it in a bit more detail, perhaps even with a bit of ASCII art?