linux-kernel - Re: [PATCH v2 3/3] md: sync blockdev before stopping raid or setting readonly

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Message-ID: <425044a0-95ce-b2a3-e98d-527c31f0313a@huaweicloud.com>
Date: Wed, 24 Jan 2024 11:16:48 +0800
From: Li Nan <linan666@...weicloud.com>
To: Mariusz Tkaczyk <mariusz.tkaczyk@...ux.intel.com>,
 linan666@...weicloud.com
Cc: song@...nel.org, shli@...com, neilb@...e.com, zlliu@...e.com,
 linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
 yukuai3@...wei.com, yi.zhang@...wei.com, houtao1@...wei.com,
 yangerkun@...wei.com
Subject: Re: [PATCH v2 3/3] md: sync blockdev before stopping raid or setting
 readonly



在 2024/1/18 16:02, Mariusz Tkaczyk 写道:
> On Wed, 17 Jan 2024 17:37:07 +0800
> linan666@...weicloud.com wrote:
> 
>> From: Li Nan <linan122@...wei.com>
>>
>> Commit a05b7ea03d72 ("md: avoid crash when stopping md array races
>> with closing other open fds.") added sync_block before stopping raid and
>> setting readonly. Later in commit 260fa034ef7a ("md: avoid deadlock when
>> dirty buffers during md_stop.") it is moved to ioctl. array_state_store()
>> was ignored. Add sync blockdev to array_state_store() now.
>>
>> Signed-off-by: Li Nan <linan122@...wei.com>

[...]

>> +
>> +	/* we will call set readonly or stop raid, sync blockdev */
>> +	if (st == clear || (mddev->pers && (st == readonly ||
>> +	    st == inactive || (st == read_auto && md_is_rdwr(mddev))))) {
>> +		err = mddev_sync_blockdev(mddev);
>> +		if (err)
>> +			return err;
>> +		clear_md_closing = true;
>> +	}
>> +
> 
> Please reorganize it a little for readability:
> I think if no mddev->pers we don't need to consider sync_blockdev at all. If
> personality is there we can probably check for read-write. If it is not
> read-write then nothing to sync. What about that:
> 
> if (mddev->pers && md_is_rdwr(mddev) &&
>      (st == clear || st == readonly || st == inactive || st == read_auto))
> 
> Please note that I didn't test it so please let me know if you see issue in
> proposed logic.
> I think that we may be able to include it in "/* No lock dependent actions */"
> switch. Please consider it too:
> 

Thanks for your review.
It is a really good idea. I will test and improve it.

> case clear:
> case readonly:
> case inactive:
> case read_auto:
>      if(!mddev->pers || !md_is_rdwr(mddev))
>            break;
>      err = mddev_sync_blockdev(mddev);
>      if (err)
>          return err;
>      clear_md_closing = true;
>      

-- 
Thanks,
Nan