From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48453) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V0Af8-0008Q2-M6 for qemu-devel@nongnu.org; Fri, 19 Jul 2013 09:23:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V0Af7-0000ZP-9Y for qemu-devel@nongnu.org; Fri, 19 Jul 2013 09:23:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31242) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V0Af6-0000ZI-UY for qemu-devel@nongnu.org; Fri, 19 Jul 2013 09:23:57 -0400 Message-ID: <51E93DDB.6070708@redhat.com> Date: Fri, 19 Jul 2013 15:23:39 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1373992168-26043-1-git-send-email-pbonzini@redhat.com> <1373992168-26043-9-git-send-email-pbonzini@redhat.com> <51E93D41.4010601@redhat.com> In-Reply-To: <51E93D41.4010601@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 08/17] block: make bdrv_has_zero_init return false for copy-on-write-images List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: famz@redhat.com, pl@kamp.de, qemu-devel@nongnu.org, stefanha@redhat.com -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Il 19/07/2013 15:21, Eric Blake ha scritto: > Question (more for my understanding, not that you need to change > code): must we blindly return 0 in the presence of a backing file, > or is it possible to recursively query the backing_hd's zero_init > status, allowing us to return 1 iff all files in the chain support > zero_init. No, it's really blind. bdrv_has_zero_init is like "was the image all zeros at creation time", and the answer is no because the content of the image used to be the same as the backing_hd. Paolo -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJR6T3bAAoJEBvWZb6bTYbyraEP/04nt2HxFsX+na7q/Ax7bGYn Z0RvyP2zTukfv8dM9aJVjmQEvLRnp7ROQlSOXPbxF3gzr2nh67nb27Xi+vF0B3N0 fDQTnnUX/8Zz2jigolDCSSFp0ggDWRtVID+W/olfIQMAJI1PkRdt0VJQp9aeLGZV 7tae/Fl5AQtfZfAW6Ji4FZzJcmLDyM7HoveZxnAawGy9e17opKGFmKUmBNutew0C LoKDkakWRrW/k4IzXB0TJOtQ5hOn5yoG16VjYG1YKblewRqaciFba62T+Z4ClJB0 TKJEr3fuGokI9mPoyPCpuZF0ZPEFFI26Mwocag8TpCS5IYJzJjC7RcGDW5CV4zzC Lzr3fGeTTtEOCJfdF4GtqeSp2S+1QWuagLLr31cV1KpnuKVLItsQ95gDpZMtqjC0 FKLkF7g/BQrE/UgGzJ16YuF4h+Ct8+2Ihiz0BS6OD6ie2g9Ds/u1l/TCn/jfj+ID PJhDUcDPynBqy+i1V475w+ZY7lLpE7oOg1HPJvQLqFgc6XkPTI75EttpWB01NOoO vKfugwxKJBfLFCX/oWbTk04P69dysLJLeb/WedTrqWAdn/to0bhD1aKX2rV+aYx3 Rs+7DescTrGV+n6qcdx2TUEqswCyMrBoStBUwEGuM+S+EVFQ7KitAY83puNUO3zX qAEpAOUWyqE0WXG3s7Ee =ltDY -----END PGP SIGNATURE-----