Re: rbd format check

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

On 11/16/2011 11:10 AM, Sage Weil wrote:
> On Wed, 16 Nov 2011, Josh Durgin wrote:
>> On 11/16/2011 10:40 AM, Sage Weil wrote:
>>> On Tue, 15 Nov 2011, Josh Durgin wrote:
>>>> I added a simple check for the old version in the wip-rbd-layering branch
>>>> of
>>>> ceph and ceph-client.git. If that looks good and you want to push it
>>>> upstream,
>>>> maybe grab the rollback removal from wip-rollback as well.
>>>
>>> On the librbd side, let's add a dout(0 or 1) so that we can figure out why
>>> things are failing.  Ideally we could use a distinct error code too so
>>> that the tools can report an appropriate error message, altho looking at
>>> errno-base.h nothing looks like an obvious choice.
>>
>> I looked through errno.h as well and didn't see anything that fit very well.
>> Anyone have a suggestion? The ones that seem closest are EBADMSG or
>> EMEDIUMTYPE.
>>
>> Also, the dout(0) errors don't seem to be printed unless you add the
>> --err-to-stderr (or stronger) flags. Shouldn't printing errors be the
>> default?
>
> Hmm, err_to_stderr should default to true... although that is probably a
> bad thing for librbd!
>
> Maybe
>
> #define ENOEXEC          8      /* Exec format error */
>
> ?

I went with ENXIO - from POSIX.1:

"No such device or address. Input or output on a special file refers to 
a device that does not exist, or makes a request beyond the capabilities 
of the device. It may also occur when, for example, a tape drive is not 
on-line."