From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:50331) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RsisN-0007XB-U9 for qemu-devel@nongnu.org; Wed, 01 Feb 2012 17:42:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RsisI-00075y-Qb for qemu-devel@nongnu.org; Wed, 01 Feb 2012 17:42:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54602) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RsisI-00075Q-JT for qemu-devel@nongnu.org; Wed, 01 Feb 2012 17:41:58 -0500 Message-ID: <4F29BFAF.9040201@redhat.com> Date: Wed, 01 Feb 2012 15:41:51 -0700 From: Eric Blake MIME-Version: 1.0 References: <20120201030557.2990.74150.sendpatchset@skannery.in.ibm.com> In-Reply-To: <20120201030557.2990.74150.sendpatchset@skannery.in.ibm.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------enig338C2964B04020CC4EA55D5F" Subject: Re: [Qemu-devel] [RFC Patch 0/7]Qemu: Dynamic host pagecache change List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Supriya Kannery Cc: Kevin Wolf , Stefan Hajnoczi , Luiz Capitulino , qemu-devel@nongnu.org, Christoph Hellwig This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig338C2964B04020CC4EA55D5F Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 01/31/2012 08:05 PM, Supriya Kannery wrote: > For changing host pagecache setting of a running VM, it is > important to have a safe way of reopening its image file. >=20 > Following patchset introduces: > * a generic way to reopen image files safely.=20 > In this approach, before reopening an image, for each > block driver, its state will be stashed. Incase preparation > (bdrv_reopen_prepare) for reopening returns success, the stashed=20 > state will be cleared (bdrv_reopen_commit) and reopened state will = > be used further. Incase preparation of reopening returns failure,=20 > the state of the driver will be rolled back (bdrv_reopen_abort)=20 > to the stashed state. > This approach is extended to raw-posix, raw-win32 and vmdk bloc= k=20 > drivers in this patchset. Once this is reviewed and finalised, I wi= ll=20 > extend the implementation to other drivers like qcow2, qed etc.. How will this interplay with the goal of passing images in by fd rather than by name? I'd really like to start thinking about how we plan on coordinating situations where an fd has to be reopened in order to switch flags (such as O_RDONLY becoming O_RDWR, or adding or subtracting O_DIRECT), but where SELinux or other isolation means that the management app (such as libvirt) has to do the open and pass the fd via 'getfd' monitor command. --=20 Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --------------enig338C2964B04020CC4EA55D5F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBCAAGBQJPKb+vAAoJEKeha0olJ0Nq8p8H/A+cZUTW5C4EhtAMUxTLjZYX ihtgMkID2FMAYiI6IDR72SkQ7uUENK5mKckiu1nE4IKPRfk1T3llgZ535FqLXiVP qWaPwPsvmtzDjyg5ts7vhjEshtRbCbIreYCrhcCq94jeENr1fF12B0uzUWcO3g5q oSeP2BXJYEnNslkTo0kYEavbl4PjJckQVl3j98W7yp0mBv2pU9VfKT9tBiE+xr62 8X3tnHwfrGzsv6VshkAcYyz/46Eq6m9PXSXLg+I12TUDTsIZW5eSf4z3s737Pdkh /VA1vBdr4URkHcFg6cMmndTCzMHGF1O31dkdkxprB5KXHu5I/rDXYbC2jt6rKNw= =ZD3K -----END PGP SIGNATURE----- --------------enig338C2964B04020CC4EA55D5F--