Re: [PATCH] md/raid0: avoid RAID0 data corruption due to layout confusion.

[Song Liu <songliubraving@fb.com>]

> On Sep 10, 2019, at 12:33 AM, NeilBrown <neilb@suse.de> wrote:
> 
> On Mon, Sep 09 2019, Song Liu wrote:
> 
>> Hi Neil,
>> 
>>> On Sep 9, 2019, at 7:57 AM, NeilBrown <neilb@suse.de> 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@vger.kernel.org (3.14+)
>>> Signed-off-by: NeilBrown <neilb@suse.de>
>> 
>> 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!

Guoqing, if this looks good, please reply with your Reviewed-by
or Acked-by. 

Thanks,
Song