From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57782) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ddRju-0000m8-U3 for qemu-devel@nongnu.org; Thu, 03 Aug 2017 21:49:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ddRjt-0000nj-TV for qemu-devel@nongnu.org; Thu, 03 Aug 2017 21:49:22 -0400 References: <20170803150301.10177-1-kwolf@redhat.com> <20170803150301.10177-3-kwolf@redhat.com> <8dfbc0ca-9a02-3620-d9e5-41aadee69d52@redhat.com> From: Eric Blake Message-ID: Date: Thu, 3 Aug 2017 20:49:11 -0500 MIME-Version: 1.0 In-Reply-To: <8dfbc0ca-9a02-3620-d9e5-41aadee69d52@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vIxR0tFdpo6sHLq1KqWM16i27oUs3SJj0" Subject: Re: [Qemu-devel] [PATCH for-2.10 2/5] block: Allow reopen rw without BDRV_O_ALLOW_RDWR List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --vIxR0tFdpo6sHLq1KqWM16i27oUs3SJj0 From: Eric Blake To: Kevin Wolf , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org Message-ID: Subject: Re: [Qemu-devel] [PATCH for-2.10 2/5] block: Allow reopen rw without BDRV_O_ALLOW_RDWR References: <20170803150301.10177-1-kwolf@redhat.com> <20170803150301.10177-3-kwolf@redhat.com> <8dfbc0ca-9a02-3620-d9e5-41aadee69d52@redhat.com> In-Reply-To: <8dfbc0ca-9a02-3620-d9e5-41aadee69d52@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 08/03/2017 10:21 AM, Eric Blake wrote: > On 08/03/2017 10:02 AM, Kevin Wolf wrote: >> BDRV_O_ALLOW_RDWR is a flag that tells whether qemu can internally >> reopen a node read-write temporarily because the user requested >> read-write for the top-level image, but qemu decided that read-only is= >> enough for this node (a backing file). >> >> bdrv_reopen() is different, it is also used for cases where the user >> changed their mind and wants to update the options. There is no reason= >> to forbid making a node read-write in that case. >=20 > Hmm, I wonder. https://bugzilla.redhat.com/show_bug.cgi?id=3D1465320 > details a failure when starting qemu with a read-write NBD disk, then > taking several snapshots (nbd <- snap1 <- snap2 <- snap3), then where > intermediate commit (snap2 into nbd) works but live commit (snap3 into > nbd) fails with a message that nbd does not support reopening. I'm > presuming that your series may help to address that; I'll give it a spi= n > and see what happens. Nope, even with your patches, I'm still getting: {'execute':'block-commit','arguments':{'device':'drive-image1','top':'bar= 2'}} {"return": {}} {"timestamp": {"seconds": 1501811285, "microseconds": 439748}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "drive-image1", "len": 2097152, "offset": 2097152, "speed": 0, "type": "commit"}} {'execute':'block-commit','arguments':{'device':'drive-image1','top':'bar= 3'}} {"error": {"class": "GenericError", "desc": "Block format 'nbd' used by node '#block048' does not support reopening files"}} --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --vIxR0tFdpo6sHLq1KqWM16i27oUs3SJj0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlmD0pcACgkQp6FrSiUn Q2q++Af/eVzxd6ukJGfUmJsVtu6kCnf3D8Ug6Z+0gT+Ejvsf0LAG8J+a2YWYCDZP ZKqbB86Rs+YoU744ZmGLSmo3Q/ubI42b9zWeoZ/gyz2h2BuU41b14lvB8xHdjKs5 ZObF+iJnk486HtP6p39EAuVaQr7aqMBfLt46s6SKOM2h+fMAIMutOyxWN6gIP19R jQRmV9BA1/yovRrSOheboVSOYOYxOkPNgxp094AHZfhyvTsv8FDkFFGouM0q7G6f +ZY7a/6795+PiBDSxyj/0gwIZYfeUr3AvLFlzr5I9utxEifZmJY5PPB7PenbZY4P wOpngLuvRSAkQ2JQ5VJa3CL6mGcm/A== =TmL5 -----END PGP SIGNATURE----- --vIxR0tFdpo6sHLq1KqWM16i27oUs3SJj0--