Re: [Xen-devel] RFC: Making QEMU honour 'readonly' flag for disks

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Daniel P. Berrange writes ("[Xen-devel] RFC: Making QEMU honour 'readonly' flag 
for disks"):
> The Xen disk configuration syntax allows a block device to be marked as
> readonly, exclusive writable or shared writeable. The xen hotplug scripts
> will clash for clashing configs between domains, but  it is upto the
> backend drivers to actually enforce the readonly flag on I/O operations.
> The paravirt backend disk driver does this fine, but QEMU's emulated
> backend driver does not.

I still think this is a fix we should have but your patch is very
intrusive.  Is there some reason why you didn't just invent
BDRV_O_RDONLY_NO__ACTUALLY__READONLY ?  A new parameter to bdrv_new
seems quite wrong.

(It's a shame that the existing BDRV_O_RDONLY does something strange
and probably wrong, but we probably don't want to fix that in our
branch.)

Would you be willing to prepare a revised patch along those lines ?
If you don't want to deal with upstream I can put your change in the
pile with the others ...

Ian.

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