[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol |
Date: |
Wed, 27 Jul 2011 09:43:04 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Jul 27, 2011 at 10:36:25AM +0200, Kevin Wolf wrote:
> Am 27.07.2011 10:22, schrieb Daniel P. Berrange:
> > On Wed, Jul 27, 2011 at 10:11:06AM +0200, Kevin Wolf wrote:
> >> Am 26.07.2011 18:57, schrieb Corey Bryant:
> >>>>>> diff --git a/block/cow.c b/block/cow.c
> >>>>>> index 4cf543c..e17f8e7 100644
> >>>>>> --- a/block/cow.c
> >>>>>> +++ b/block/cow.c
> >>>>>> @@ -82,6 +82,11 @@ static int cow_open(BlockDriverState *bs, int
> >>>>>> flags)
> >>>>>> pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> >>>>>> cow_header.backing_file);
> >>>>>>
> >>>>>> + if (bs->backing_file[0] != '\0'&& bdrv_is_fd_protocol(bs)) {
> >>>>>> + /* backing file currently not supported by fd: protocol */
> >>>>>> + goto fail;
> >>>>>> + }
> >>>> I don't think these checks are strictly needed. Without the check you
> >>>> can open the image itself using an fd, and the backing file using good
> >>>> old raw-posix. We shouldn't decide for our users that this isn't useful.
> >>>>
> >>>> In any case, it would have to move into block.c, you can't modify
> >>>> independent drivers for this.
> >>>>
> >>>
> >>> I understand the point on not modifying independent drivers.
> >>>
> >>> But if the backing file resides on NFS, wouldn't the the proposed
> >>> SELinux changes prevent the open?
> >>
> >> Probably. But what about cases where the backing file is local? Or even
> >> a non-libvirt, non-SELinux use case?
> >>
> >>> Or are you talking about support where libvirt opens the backing file
> >>> and passes the fd to Qemu? If so there was some discussion about future
> >>> support for this here:
> >>> http://lists.gnu.org/archive/html/qemu-devel/2011-06/msg01496.html
> >>
> >> Not really, but implementing this will be a bit easier if you don't
> >> forbid using backing files with fd.
> >
> > In any case, for 'fd:' to be actually used by libvirt, we need to have
> > backing files supported. There are major users of libvirt who rely on
> > NFS and also use backing files, so an 'fd:' impl which can't deal with
> > the backing file problem isn't much use to libvirt.
>
> I'm perfectly aware of that. But seriously, repeating it over and over
> again isn't going to make it happen any sooner. It requires -blockdev
> which we may or may not have by 1.0.
Yes, I understand we need also -blockdev for this. Other messages in this
mail thread have impied that this proposed patch on its own is useful for
libvirt's requirements, so I just wanted to remind people in general that
we can't use this patch on its own until we have something like -blockdev.
Regards,
Daniel
--
|: 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 :|
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, (continued)
- Re: [Qemu-devel] [libvirt] [PATCH v3] Add support for fd: protocol, Eric Blake, 2011/07/26
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Kevin Wolf, 2011/07/26
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Corey Bryant, 2011/07/26
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Kevin Wolf, 2011/07/27
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Daniel P. Berrange, 2011/07/27
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Kevin Wolf, 2011/07/27
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol,
Daniel P. Berrange <=
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Corey Bryant, 2011/07/27
- Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Kevin Wolf, 2011/07/27
Re: [Qemu-devel] [PATCH v3] Add support for fd: protocol, Blue Swirl, 2011/07/27