From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:55201) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RpOhi-0004pB-VT for qemu-devel@nongnu.org; Mon, 23 Jan 2012 13:33:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RpOhh-00044d-Cp for qemu-devel@nongnu.org; Mon, 23 Jan 2012 13:33:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:25936) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RpOhh-00044D-1f for qemu-devel@nongnu.org; Mon, 23 Jan 2012 13:33:17 -0500 Date: Mon, 23 Jan 2012 18:32:47 +0000 From: "Daniel P. Berrange" Message-ID: <20120123183247.GB14752@redhat.com> References: <1326737500-11202-1-git-send-email-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1326737500-11202-1-git-send-email-berrange@redhat.com> Subject: Re: [Qemu-devel] [PATCH] Remove O_NOATIME flag from 9pfs open() calls in readonly mode Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, "Aneesh Kumar K.V" Cc: "M. Mohan Kumar" Any thoughts on this fix ? Read-only mode is pretty useless without it for non-root users. Daniel On Mon, Jan 16, 2012 at 06:11:40PM +0000, Daniel P. Berrange wrote: > From: "Daniel P. Berrange" > > When 2c74c2cb4bedddbfa67628fbd5f9273b4e0e9903 added support for > the 'readonly' flag against 9p filesystems, it also made QEMU > add the O_NOATIME flag as a side-effect. > > The O_NOATIME flag, however, may only be set by the file owner, > or a user with CAP_FOWNER capability. QEMU cannot assume that > this is the case for filesytems exported to QEMU. > > eg, run QEMU as non-root, and attempt to pass the host OS > filesystem through to the guest OS with readonly enable. > The result is that the guest OS cannot open any files at > all. > > If O_NOATIME is really required, it should be optionally > enabled via a separate QEMU command line flag. > > * hw/9pfs/virtio-9p.c: Remove O_NOATIME > > Signed-off-by: Daniel P. Berrange > --- > hw/9pfs/virtio-9p.c | 1 - > 1 files changed, 0 insertions(+), 1 deletions(-) > > diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c > index e6ba6ba..f8e2c07 100644 > --- a/hw/9pfs/virtio-9p.c > +++ b/hw/9pfs/virtio-9p.c > @@ -1391,7 +1391,6 @@ static void v9fs_open(void *opaque) > err = -EROFS; > goto out; > } > - flags |= O_NOATIME; > } > err = v9fs_co_open(pdu, fidp, flags); > if (err < 0) { > -- > 1.7.7.5 > -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|