From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35586) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ePw1G-0002Qr-0y for qemu-devel@nongnu.org; Fri, 15 Dec 2017 14:51:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ePw1F-00012b-8y for qemu-devel@nongnu.org; Fri, 15 Dec 2017 14:51:42 -0500 References: <20171215080446.10671-1-famz@redhat.com> From: Eric Blake Message-ID: Date: Fri, 15 Dec 2017 13:51:29 -0600 MIME-Version: 1.0 In-Reply-To: <20171215080446.10671-1-famz@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="BHLM5qXXEObXo8lmceGLuGR4UNpUPtf5x" Subject: Re: [Qemu-devel] [PATCH 0/2] block: Fix qemu-img creating overlay when guest running List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Max Reitz This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --BHLM5qXXEObXo8lmceGLuGR4UNpUPtf5x From: Eric Blake To: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Max Reitz Message-ID: Subject: Re: [Qemu-devel] [PATCH 0/2] block: Fix qemu-img creating overlay when guest running References: <20171215080446.10671-1-famz@redhat.com> In-Reply-To: <20171215080446.10671-1-famz@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 12/15/2017 02:04 AM, Fam Zheng wrote: > Shared write lock is not strictly necessary for creating the overlay im= age, if > all what we want is to probe the size. Theoretically, the size could be changing due to a resize operation. But realistically, even if that happens, we will (hopefully) see either the old size or the new size atomically (that is, I seriously doubt the size information is split across multiple sectors of the in-use image to the point that we could shard the read). Series: Reviewed-by: Eric Blake --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --BHLM5qXXEObXo8lmceGLuGR4UNpUPtf5x 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/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlo0J8EACgkQp6FrSiUn Q2oENwf/UCatBQx0/VMl9CwDi5lo1v/ysSQj8raLj8mNUZQjudv2M9u/aidUG+sa JUTgdmUp50heurPAw4fmnRvMLhPxGezmxbYTSWcDsj/NMR6Uc84qEJBBd4M2LOI0 y/5OyRXjGxrMLrDy5jEvAWfFrq7sUCT2EZh8AXUq89s5C64PbO4O7QLJ4oLIkak4 d9blebi0HMPKMFk4b6+XaM1hnOSQ2we2WCX7rCmknt+rglg3lfwN2xRaFUpUIyDx +AaLfmqM0bOjqCBS+VHtGpwB+SBY5s7+C7JBB/GUSsBDTgYVtAXt1zaztP4V5xES gFwP4c8YHl913DKyGbRC5+tUBrqXHg== =KMaw -----END PGP SIGNATURE----- --BHLM5qXXEObXo8lmceGLuGR4UNpUPtf5x--