On Tue, Sep 10 2019, Guoqing Jiang wrote:
> On 9/10/19 5:45 PM, Song Liu wrote:
>>
>>
>>> On Sep 10, 2019, at 12:33 AM, NeilBrown <neilb@xxxxxxx> wrote:
>>>
>>> On Mon, Sep 09 2019, Song Liu wrote:
>>>
>>>> Hi Neil,
>>>>
>>>>> On Sep 9, 2019, at 7:57 AM, NeilBrown <neilb@xxxxxxx> wrote:
>>>>>
>>>>>
>>>>> If the drives in a RAID0 are not all the same size, the array is
>>>>> divided into zones.
>>>>> The first zone covers all drives, to the size of the smallest.
>>>>> The second zone covers all drives larger than the smallest, up to
>>>>> the size of the second smallest - etc.
>>>>>
>>>>> A change in Linux 3.14 unintentionally changed the layout for the
>>>>> second and subsequent zones. All the correct data is still stored, but
>>>>> each chunk may be assigned to a different device than in pre-3.14 kernels.
>>>>> This can lead to data corruption.
>>>>>
>>>>> It is not possible to determine what layout to use - it depends which
>>>>> kernel the data was written by.
>>>>> So we add a module parameter to allow the old (0) or new (1) layout to be
>>>>> specified, and refused to assemble an affected array if that parameter is
>>>>> not set.
>>>>>
>>>>> Fixes: 20d0189b1012 ("block: Introduce new bio_split()")
>>>>> cc: stable@xxxxxxxxxxxxxxx (3.14+)
>>>>> Signed-off-by: NeilBrown <neilb@xxxxxxx>
>>>>
>>>> Thanks for the patches. They look great. However, I am having problem
>>>> apply them (not sure whether it is a problem on my side). Could you
>>>> please push it somewhere so I can use cherry-pick instead?
>>>
>>> I rebased them on block/for-next, fixed the problems that Guoqing found,
>>> and pushed them to
>>> https://github.com/neilbrown/linux md/raid0
>>>
>>> NeilBrown
>>
>> Thanks Neil!
>
> Thanks for the explanation about set the flag.
>
>>
>> Guoqing, if this looks good, please reply with your Reviewed-by
>> or Acked-by.
>
> No more comments from my side, but I am not sure if it is better/possible to use one
> sysfs node to control the behavior instead of module parameter, then we can support
> different raid0 layout dynamically.
A strength of module parameters is that you can set them in
/etc/modprobe.d/00-local.conf
and then they are automatically set on boot.
For sysfs, you need some tool to set them.
>
> Anyway, Acked-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
>
Thanks,
NeilBrown
> Thanks,
> Guoqing
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