linux-kernel - Re: [PATCH -next 1/5] md/raid5: don't allow replacement while reshape is not done

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Message-ID: <aad4acb6-ccc7-560e-e251-3b4b28a862ef@huaweicloud.com>
Date:   Mon, 22 May 2023 11:46:08 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     Song Liu <song@...nel.org>, Yu Kuai <yukuai1@...weicloud.com>
Cc:     logang@...tatee.com, reddunur@...ine.de, jovetoo@...il.com,
        dgilmour76@...il.com, linux-raid@...r.kernel.org,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
        yangerkun@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH -next 1/5] md/raid5: don't allow replacement while reshape
 is not done

Hi,

在 2023/05/20 7:33, Song Liu 写道:
> On Thu, May 11, 2023 at 6:59 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> Set rdev replacement has but not only two conditions:
>>
>> 1) MD_RECOVERY_RUNNING is not set;
>> 2) rdev nr_pending is 0;
> 
> The above is confusing. I updated it and applied the set to md-next.

By the way, I'm willing to add regression test for these problems, and I
already send two other tests and there are no response yet. Should the
test wait for fixed patch to be applied to make progress?

Thanks,
Kuai
> Please let me know if it looks good.
> 
> Thanks,
> Song
> 
>>
>> If reshape is interrupted(for example, echo frozen to sync_action), then
>> rdev replacement can be set. It's safe because reshape is always prior to
>> resync in md_check_recovery(). However, if system reboots, then kernel will
>> complain cannot handle concurrent replacement and reshape and this array
>> is not able to assemble anymore.
>>
>> Fix this problem by don't allow replacement until reshape is done.
>>
>> Reported-by: Peter Neuwirth <reddunur@...ine.de>
>> Link: https://lore.kernel.org/linux-raid/e2f96772-bfbc-f43b-6da1-f520e5164536@online.de/
>> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   drivers/md/raid5.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index a58507a4345d..bd3b535c0739 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -8378,6 +8378,7 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>>                  p = conf->disks + disk;
>>                  tmp = rdev_mdlock_deref(mddev, p->rdev);
>>                  if (test_bit(WantReplacement, &tmp->flags) &&
>> +                   mddev->reshape_position == MaxSector &&
>>                      p->replacement == NULL) {
>>                          clear_bit(In_sync, &rdev->flags);
>>                          set_bit(Replacement, &rdev->flags);
>> --
>> 2.39.2
>>
> .
>