From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46988) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XCRyq-0006Db-81 for qemu-devel@nongnu.org; Wed, 30 Jul 2014 07:23:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XCRyl-0005dr-9F for qemu-devel@nongnu.org; Wed, 30 Jul 2014 07:23:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21098) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XCRyl-0005dl-13 for qemu-devel@nongnu.org; Wed, 30 Jul 2014 07:23:31 -0400 Message-ID: <53D8D5AF.2000704@redhat.com> Date: Wed, 30 Jul 2014 05:23:27 -0600 From: Eric Blake MIME-Version: 1.0 References: <1406710411-26373-1-git-send-email-stefanha@redhat.com> <1406710411-26373-2-git-send-email-stefanha@redhat.com> In-Reply-To: <1406710411-26373-2-git-send-email-stefanha@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="r3FDgdv9MrgvjAgH9p1JqmViRvjOUATBP" Subject: Re: [Qemu-devel] [PATCH v2 1/2] block: fix overlapping multiwrite requests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , qemu-devel@nongnu.org Cc: Kevin Wolf , andrey@xdel.ru, Fam Zheng , sviatoslav.pestov@gmail.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --r3FDgdv9MrgvjAgH9p1JqmViRvjOUATBP Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 07/30/2014 02:53 AM, Stefan Hajnoczi wrote: > When request A is a strict superset of request B: >=20 > AAAAAAAA > BBBB >=20 > multiwrite_merge() merges them as follows: >=20 > AABBBB >=20 > The tail of request A should have been included: >=20 > AABBBBAA >=20 > This patch fixes data loss but this code path is probably rare. Since > guests cannot assume ordering between in-flight requests, few > applications submit overlapping write requests. >=20 > Reported-by: Slava Pestov > Signed-off-by: Stefan Hajnoczi > --- > block.c | 6 ++++++ > 1 file changed, 6 insertions(+) >=20 Reviewed-by: Eric Blake Technically a bug fix, so okay for 2.1 if desired; but it is awfully late and as you said it is fairly unlikely for guests to be relying on overlapping multiwrite, so I'm okay with the decision to delay it to 2.2 and just have stable 2.1.1/downstream backports. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --r3FDgdv9MrgvjAgH9p1JqmViRvjOUATBP Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg iQEcBAEBCAAGBQJT2NWvAAoJEKeha0olJ0NqawgIAKSYqvgbYJ99Y6aH8IiQUGAX Ow89PSLpT5ieGjQYUw9Lu+KQR+mDdeNd5FKljGd6xEvliYJ97qcTOLHu6uM5RbUp mSHoSz3oDB/e7HfaAQtUYQCQwllgjGkzAks5Mddc7y/iRkytEFYF8pHfGTj7cjhr 84G9fzyk6gyVAO4CWMNBczEj5/HgqPHnG22rwNvo9RrlnCgOOE59dEinIirKOt4P RO4WLBisIMIAeiG+ztJh3oOH5vQEY01uXz5AfIdTFv7sw2Qo7cWQV3jaPEZjCPXS TlbVK1o3SLS/OHExRhgxrFNImysK/YkUq4FVFC6oHWIXqW/9ONCKMbyIQwNG7vo= =zXs6 -----END PGP SIGNATURE----- --r3FDgdv9MrgvjAgH9p1JqmViRvjOUATBP--