linux-kernel - Re: [PATCH -next 0/2] block: fix scan partition for exclusively open device again

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Date:   Wed, 22 Mar 2023 09:26:07 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     Ming Lei <ming.lei@...hat.com>, Yu Kuai <yukuai1@...weicloud.com>
Cc:     jack@...e.cz, hare@...e.de, hch@...radead.org, axboe@...nel.dk,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com, yangerkun@...wei.com,
        "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH -next 0/2] block: fix scan partition for exclusively open
 device again

Hi,

在 2023/03/21 19:43, Ming Lei 写道:
> On Fri, Feb 17, 2023 at 10:21:58AM +0800, Yu Kuai wrote:
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> Changes from RFC:
>>   - remove the patch to factor out GD_NEED_PART_SCAN
>>
>> Yu Kuai (2):
>>    block: Revert "block: Do not reread partition table on exclusively
>>      open device"
>>    block: fix scan partition for exclusively open device again
> 
> Hi Yu kuai,
> 
> Looks the original issue starts to re-appear now with the two patches:
> 
> https://lore.kernel.org/linux-block/20221130135344.2ul4cyfstfs3znxg@quack3/
> 
> And underlying disk partition and raid partition can be observed at the
> same time.
> 
> Can you take a look?
Yes, thanks for the report. I realize that sda1 adn sdb1 is created
while raid open sda and sdb excl, and I think this problem should exist
before this patchset.

And I verify this with following test:

1) mdadm -CR /dev/md0 -l 1 -n 2 /dev/sda /dev/sdb -e 1.0
2) sgdisk -n 0:0:+100MiB /dev/md0
3) mdadm -S /dev/md0
# scan partitions of sda
4) blockdev --rereadpt /dev/sda

Then sda1 is created.

I'm not sure how to fix this yet😂

Thanks,
Kuai
> 
> Follows the script, which isn't 100% triggered, but still easy.
> 
> #create level 1 with 2 devices, meta 1.0
> mdadm -CR /dev/md0 -l 1 -n 2 /dev/sda /dev/sdb -e 1.0
> 
> #create partition 0, start from 0 sector, size 100MiB
> sgdisk -n 0:0:+100MiB /dev/md0
> 
> #observe partitions
> cat /proc/partitions
> 
> #stop the array
> mdadm -S /dev/md0
> 
> #re-assemble
> mdadm -A /dev/md0 /dev/sda /dev/sdb
> cat /proc/partitions
> 
> 
> Thanks,
> Ming
> 
> .
>