linux-kernel - Re: [PATCH -next] md/raid5: don't allow concurrent reshape with recovery

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Message-ID: <7932f1dd-ad0a-a744-39f4-b38b364ab486@huaweicloud.com>
Date:   Mon, 29 May 2023 21:36:55 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     Paul Menzel <pmenzel@...gen.mpg.de>,
        Yu Kuai <yukuai1@...weicloud.com>
Cc:     song@...nel.org, 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] md/raid5: don't allow concurrent reshape with
 recovery

Hi,

在 2023/05/29 14:44, Paul Menzel 写道:
> Dear Yu,
> 
> 
> Thank you for your patch. As always some minor commons, you can also 
> ignore.

Thanks for there comments, I'll update them in v2 except that 'unsigned
int i'.

Thanks,
Kuai
> 
> Am 29.05.23 um 05:10 schrieb Yu Kuai:
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> commit 0aecb06e2249 ("md/raid5: don't allow replacement while reshape
> 
> I’d start with a capital letter: Commit …
> 
>> is in progress") fix that replacement can be set if reshape is
> 
> fixes
> 
>> interrupted, which will cause that array can't be assemebled.
> 
> assembled
> 
>> There is a similar on the other side, if recovery is interrupted, then
> 
> similar *problem*?
> 
>> reshape can start, which will cause the same problem.
>>
>> Fix the prblem by don't start reshape is recovery is still in progress.
> 
> •  problem
> •  … by not starting to reshape while recovery is still in progress
> 
>> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   drivers/md/raid5.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index 64865f9dd3f5..6db783ca71b7 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -8500,6 +8500,7 @@ static int raid5_start_reshape(struct mddev *mddev)
>>       struct r5conf *conf = mddev->private;
>>       struct md_rdev *rdev;
>>       int spares = 0;
>> +    int i;
> 
> It won’t make a difference for the code I believe, but as the count 
> variable can’t be negative, I’d use `unsigned int`.
> 
>>       unsigned long flags;
>>       if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
>> @@ -8511,6 +8512,13 @@ static int raid5_start_reshape(struct mddev 
>> *mddev)
>>       if (has_failed(conf))
>>           return -EINVAL;
>> +    /* raid5 can't handle concurrent reshape and recovery */
>> +    if (mddev->recovery_cp < MaxSector)
>> +        return -EBUSY;
>> +    for (i = 0; i < conf->raid_disks; i++)
>> +        if (rdev_mdlock_deref(mddev, conf->disks[i].replacement))
>> +            return -EBUSY;
>> +
>>       rdev_for_each(rdev, mddev) {
>>           if (!test_bit(In_sync, &rdev->flags)
>>               && !test_bit(Faulty, &rdev->flags))
> 
> 
> Kind regards,
> 
> Paul
> 
> .
>