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From: NeilBrown <neilb@suse.de>
To: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>,
	Song Liu <songliubraving@fb.com>,
	Guoqing Jiang <jgq516@gmail.com>
Cc: Coly Li <colyli@suse.de>, NeilBrown <neilb@suse.com>,
	"linux-block\@vger.kernel.org" <linux-block@vger.kernel.org>,
	linux-raid <linux-raid@vger.kernel.org>
Subject: Re: [PATCH] md/raid0: avoid RAID0 data corruption due to layout confusion.
Date: Wed, 11 Sep 2019 09:08:25 +1000	[thread overview]
Message-ID: <877e6fbvh2.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <58722139-ebc0-f49f-424a-c3b1aa455dd8@cloud.ionos.com>

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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@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!
>
> 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@cloud.ionos.com>
>

Thanks,
NeilBrown


> Thanks,
> Guoqing

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  reply	other threads:[~2019-09-10 23:08 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-22 10:38 [RFC] How to handle an ugly md raid0 sector map bug ? Coly Li
2019-08-23  0:02 ` NeilBrown
2019-08-23 16:37   ` Song Liu
2019-08-23 17:03     ` Coly Li
2019-08-23 17:17       ` Song Liu
2019-08-23 17:47         ` Coly Li
2019-09-09  6:57           ` [PATCH] md/raid0: avoid RAID0 data corruption due to layout confusion NeilBrown
2019-09-09  6:58             ` [PATCH 2/2] md: add feature flag MD_FEATURE_RAID0_LAYOUT NeilBrown
2019-09-09 15:33               ` Guoqing Jiang
2019-09-09 23:26                 ` NeilBrown
2019-09-09 14:56             ` [PATCH] md/raid0: avoid RAID0 data corruption due to layout confusion Song Liu
2019-09-09 23:33               ` NeilBrown
2019-09-10 15:45                 ` Song Liu
2019-09-10 16:01                   ` Guoqing Jiang
2019-09-10 23:08                     ` NeilBrown [this message]
2019-09-11  9:56                       ` Song Liu
2019-09-11 22:48                         ` NeilBrown
2019-09-09 15:09             ` Guoqing Jiang
2019-09-09 23:34               ` NeilBrown

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