linux-kernel - Re: [PATCH md-6.12 3/7] md: don't record new badblocks for faulty rdev

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Message-ID: <c9af88ac-111e-19a2-b135-d2a379ed23fc@huaweicloud.com>
Date: Sat, 31 Aug 2024 09:14:39 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Mariusz Tkaczyk <mariusz.tkaczyk@...ux.intel.com>,
 Yu Kuai <yukuai1@...weicloud.com>
Cc: mariusz.tkaczyk@...el.com, 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 md-6.12 3/7] md: don't record new badblocks for faulty
 rdev

Hi,

在 2024/08/30 18:28, Mariusz Tkaczyk 写道:
> On Fri, 30 Aug 2024 15:27:17 +0800
> Yu Kuai <yukuai1@...weicloud.com> wrote:
> 
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> Faulty will be checked before issuing IO to the rdev, however, rdev can
>> be faulty at any time, hence it's possible that rdev_set_badblocks()
>> will be called for faulty rdev. In this case, mddev->sb_flags will be
>> set and some other path can be blocked by updating super block.
>>
>> Since faulty rdev will not be accesed anymore, there is no need to
>> record new babblocks for faulty rdev and forcing updating super block.
>>
>> Noted this is not a bugfix, just prevent updating superblock in some
>> corner cases, and will help to slice a bug related to external
>> metadata[1].
>>
>> [1]
>> https://lore.kernel.org/all/f34452df-810b-48b2-a9b4-7f925699a9e7@linux.intel.com/
>>
>> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   drivers/md/md.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 675d89597c7b..a3f7f407fe42 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -9757,6 +9757,10 @@ int rdev_set_badblocks(struct md_rdev *rdev, sector_t
>> s, int sectors, {
>>   	struct mddev *mddev = rdev->mddev;
>>   	int rv;
>> +
>> +	if (test_bit(Faulty, &rdev->flags))
>> +		return 1;
>> +
> 
> Blame is volatile, this is why we need a comment here :)
> Otherwise, someone may remove that.

Perhaps something like following?

/*
  * record new babblocks for faulty rdev will force unnecessary
  * super block updating.
  */

Thanks,
Kuai

> 
> Thanks,
> Mariusz
> 
> 
> .
>