[pve-devel] [Qemu-devel] [PATCH] use int64_t for return values from rbd instead of int

[Stefan Hajnoczi]

On Tue, Nov 20, 2012 at 8:16 PM, Stefan Priebe <s.priebe at profihost.ag> wrote:
> Hi Stefan,
>
> Am 20.11.2012 17:29, schrieb Stefan Hajnoczi:
>
>> On Tue, Nov 20, 2012 at 01:44:55PM +0100, Stefan Priebe wrote:
>>>
>>> rbd / rados tends to return pretty often length of writes
>>> or discarded blocks. These values might be bigger than int.
>>>
>>> Signed-off-by: Stefan Priebe <s.priebe at profihost.ag>
>>> ---
>>>   block/rbd.c |    4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>>
>> Looks good but I want to check whether this fixes an bug you've hit?
>> Please indicate details of the bug and how to reproduce it in the commit
>> message.
>
>
> you get various I/O errors in client. As negative return values indicate I/O
> errors. When now a big positive value is returned by librbd block/rbd tries
> to store this one in acb->ret which is an int. Then it wraps around and is
> negative. After that block/rbd thinks this is an I/O error and report this
> to the guest.

It's still not clear whether this is a bug that you can reproduce.
After all, the ret value would have to be >2^31 which is a 2+ GB
request!

I'm asking if this is a critical bug fix that needs to go into QEMU
1.3-rc1 because of a real-world issue?

Stefan