Re: krbd + format=2 ?

[Josh Durgin <josh.durgin@inktank.com>]

On 06/11/2013 09:59 PM, Chris Dunlop wrote:
> On Sat, Jun 08, 2013 at 12:48:52PM +1000, Chris Dunlop wrote:
>> On Fri, Jun 07, 2013 at 11:54:20AM -0500, Alex Elder wrote:
>>> On 06/03/2013 04:24 AM, Chris Dunlop wrote:
>>>> I pulled the for-linus branch (@ 3abef3b) on top of 3.10.0-rc4, and it's
>>>> letting me map a format=2 image (created under bobtail), however reading
>>>> from the block device returns zeros rather than the data. The same image
>>>> correctly shows data (NTFS filesystem) when mounted into kvm using librbd.
>>>
>>> Have you tried using a format 2 image that you created using
>>> the Linux rbd environment?  It would be good to know whether
>>> that works for you.
>>
>> Sorry, how to you mean "created using the Linux rbd environment"?
>> The one I was trying was created using:
>>
>> rbd create --format 2 xxx --size nnnnn
>>
>> ...then populated using qemu/librbd.
>
> Looks like the kernel rbd and librbd aren't compatible, as at
> 3.10.0-rc4+ceph-client/for-linus@3abef3b vs librbd1 0.56.6-1~bpo70+1.

Thanks for the detailed report Chris. The kernel client was using the
wrong object names for format 2 (zero-padding them with a different
length than librbd). I just posted a patch fixing this.

Josh