[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening

From: Daniel P. Berrange
Subject: Re: [Qemu-devel] [PATCH v4 00/27] block: Lock images when opening
Date: Tue, 10 May 2016 09:50:41 +0100
User-agent: Mutt/1.6.0 (2016-04-01)

On Tue, May 10, 2016 at 09:43:04AM +0100, Richard W.M. Jones wrote:
> On Tue, May 10, 2016 at 09:14:26AM +0100, Richard W.M. Jones wrote:
> > However I didn't test the write-shareable case (the libvirt
> > <shareable/> flag which should map to a shared lock -- is that right Dan?).
> To Dan (mainly): I think setting the <shareable/> flag in libvirt only
> sets cache=unsafe on the qemu drive (it may have other effects for
> virtlockd).  Should there be an extra qemu drive flag to communicate
> that the drive is write-shareable?

Sure, if QEMU had a way to indicate that the disk was used in a
write-sharable mode, libvirt would use it.

I agree with your general point that we should do no locking for
read-only access, F_RDLCK for shared-write and F_WRLCK for
exclusive-write access. I think I made that point similarly against
an earlier version of this patchset

|: 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 :|

reply via email to

[Prev in Thread] Current Thread [Next in Thread]