Re: [Qemu-devel] [PATCH RFC v3 for-2.9 08/11] rbd: Revert -blockdev and -drive parameter auth-supported

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 03/27/2017 01:31 PM, Markus Armbruster wrote:
>
>>>> -
>>>> -##
>>>> -# @RbdAuthMethod:
>>>> -#
>>>> -# An enumeration of rados auth_supported types
>>>> -#
>>>> -# Since: 2.9
>>>> -##
>>>> -{ 'struct': 'RbdAuthMethod',
>>>> -  'data': { 'auth': 'RbdAuthSupport' } }
>>>> -
>>>
>>> Removing the .json QMP support is fine. But I'm reluctant to give R-b
>>> without knowing for sure that -drive usage won't regress.
>> 
>> auth-supported landed in master only on March 2nd.
>
> auth-supported via -blockdev-add only landed on March 2nd.  But
> auth-supported via -drive landed in commit 60390a2, Jan 2016; and is in
> use by libvirt:
>
> src/qemu/qemu_command.c:
> ":key=%s:auth_supported=cephx\\;none",

That's a key-value part of the pseudo-filename.  *Not* reverted by this
patch.  Only QemuOpts parameter auth_supported is.

QemuOpts parameter: -drive driver=rbd,auth_supported.0.auth=none,...
Pseudo-filename:    -drive file=rbd:...:auth_supported=none

>> What libvirt usage exactly do you think this could break?
>> 
>
> Libvirt has been managing rbd drives using -drive since at least libvirt
> commit 5745cd1, in Nov 2011, where even back then it was passing:
>             virBufferEscape(opt, ":", ":key=%s:auth_supported=cephx none",
>
> (back when it used space instead of ; to separate the list of supported
> auth types).
>
> As I've never personally used RBD (whether through qemu directly, or
> through libvirt), I'm extremely wary of breaking -drive usage that
> "works" (for some definition of "works"), even though I have no qualms
> making the QMP interface extremely limited.

All clear now?