From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:33700) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gkEuy-0006sh-2W for qemu-devel@nongnu.org; Thu, 17 Jan 2019 16:09:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gkEuu-0000eo-1y for qemu-devel@nongnu.org; Thu, 17 Jan 2019 16:09:37 -0500 References: <20180609151758.17343-1-vsementsov@virtuozzo.com> <20180609151758.17343-5-vsementsov@virtuozzo.com> <91a97b47-abab-4508-09d5-a12ddd1a4101@redhat.com> From: John Snow Message-ID: <584b60bb-e5cd-6678-0988-a9ee825d0064@redhat.com> Date: Thu, 17 Jan 2019 16:09:20 -0500 MIME-Version: 1.0 In-Reply-To: <91a97b47-abab-4508-09d5-a12ddd1a4101@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v5 4/6] nbd/server: implement dirty bitmap export List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: kwolf@redhat.com, pbonzini@redhat.com, den@openvz.org, armbru@redhat.com, mreitz@redhat.com On 1/9/19 2:21 PM, Eric Blake wrote: > Why are we restricting things to only export disabled bitmaps? Late reply, but the original thought almost surely was that we would only be exporting bitmaps for fleecing use, which should have a non-changing bitmap attached to it. Just some error checking to make sure the user didn't accidentally use the live copy attached to the active disk image, versus the one prepared for this purpose. If that's not true anymore, that's fine if the NBD server can handle the bits changing while it responds to requests... especially if a client wants to just watch the bitmap change live and query sectors every now and again, but it's a different use case from the one fairly targeted one we were pursuing at the time. --js