linux-kernel - Re: [PATCH -next v3 6/7] md: factor out a helper rdev_addable() from remove_and_add

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Date:   Thu, 24 Aug 2023 09:16:19 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     Song Liu <song@...nel.org>, Yu Kuai <yukuai1@...weicloud.com>
Cc:     xni@...hat.com, mariusz.tkaczyk@...ux.intel.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 v3 6/7] md: factor out a helper rdev_addable() from
 remove_and_add_spares()

Hi,

在 2023/08/23 19:25, Song Liu 写道:
> On Wed, Aug 23, 2023 at 1:37 AM Yu Kuai <yukuai1@...weicloud.com> wrote:
>>
> [...]
>>> diff --git i/drivers/md/md.c w/drivers/md/md.c
>>> index 78be7811a89f..8cb855d03e0a 100644
>>> --- i/drivers/md/md.c
>>> +++ w/drivers/md/md.c
>>> @@ -9117,6 +9117,20 @@ void md_do_sync(struct md_thread *thread)
>>>    }
>>>    EXPORT_SYMBOL_GPL(md_do_sync);
>>>
>>> +static bool rdev_addable(struct md_rdev *rdev)
>>> +{
>>> +       if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
>>> +           test_bit(Faulty, &rdev->flags))
>>> +               return false;
>>> +       return true;
>>> +}
>>> +
>>> +static bool rdev_is_readd(struct md_rdev *rdev)
>>> +{
>>> +       return rdev->saved_raid_disk >= 0 ||
>>> +               !test_bit(Bitmap_sync, &rdev->flags);
>> This should use '&&' instead of '||' ?
>>
>>> +}
>>> +
>>>    static int remove_and_add_spares(struct mddev *mddev,
>>>                                    struct md_rdev *this)
>>>    {
>>> @@ -9176,25 +9190,24 @@ static int remove_and_add_spares(struct mddev *mddev,
>>>           rdev_for_each(rdev, mddev) {
>>>                   if (this && this != rdev)
>>>                           continue;
>>> -               if (test_bit(Candidate, &rdev->flags))
>>> -                       continue;
>>>                   if (rdev->raid_disk >= 0 &&
>>>                       !test_bit(In_sync, &rdev->flags) &&
>>>                       !test_bit(Journal, &rdev->flags) &&
>>>                       !test_bit(Faulty, &rdev->flags))
>>>                           spares++;
>>> -               if (rdev->raid_disk >= 0)
>>> +
>>> +               if (!rdev_addable(rdev))
>>>                           continue;
>>> -               if (test_bit(Faulty, &rdev->flags))
>>> +
>>> +               if (test_bit(Journal, &rdev->flags))
>>> +                       goto hot_add_disk;
>>> +
>>
>> I understand what you mean now, but I must use the exact same judgement
>> in the new helper md_spares_need_change() in patch 7, there will be
>> redundant code this way.
>>
>> How about this, rework rdev_addable():
> 
> Yeah, this was another option that I was thinking about. Let's go with
> this version.
> 
Ok, and I'll do this for rdev_removeable() in patch 4 as well.

Thanks,
Kuai

> Thanks,
> Song
> 
>>
>>     static bool rdev_addable(struct md_rdev *rdev)
>>     {
>> +         /* rdev is already used, don't add it again. */
>>             if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
>>                 test_bit(Faulty, &rdev->flags))
>>                     return false;
>>
>> ~         /* Allow to add journal disk. */
>> ~         if (test_bit(Journal, &rdev->flags))
>> ~_                return true;
>>
>> ~         /* Allow to add if array is read-write. */
>> +         if (md_is_rdwr(rdev->mddev))
>> +                 return true;
>> +
>> +         /*
>> +          * For read-only array, only allow to readd a rdev. And if
>> bitmap is
>> +          * used, don't allow to readd a rdev that is too old.
>> +          */
>> +         if (rdev->saved_raid_disk >=0 && !test_bit(Bitmap_sync,
>> &rdev->flags))
>> +                 return true;
>> +
>> +         return false;
>>     }
> .
>