[libvirt] [PATCH v2] qemu-migration: Disallow migration of read only disk

[Daniel P. Berrange]

On Tue, Sep 20, 2016 at 03:53:16PM +0200, Peter Krempa wrote:
> On Tue, Sep 20, 2016 at 09:40:22 -0400, Corey S. McQuay wrote:
> > Currently Libvirt allows attempts to migrate read only disks. Qemu cannot handle this as read only
> > disks cannot be written to on the destination system. The end result is a cryptic error message
> > and a failed migration.
> 
> This is not necessarily true. Read only disks can sometimes be in fact
> backed by storage that is writable and it's desired to be migrated.

If 'def->readonly' is true, then the security drivers won't allow
QEMU to write to the image, regardless of whether the underlying
storage is writable.

Regards,
Daniel
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