linux-kernel - Re: [PATCH v2 1/3] md: Don't clear MD_CLOSING when the raid is about to stop

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Date: Thu, 18 Jan 2024 08:35:25 +0100
From: Mariusz Tkaczyk <mariusz.tkaczyk@...ux.intel.com>
To: 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 1/3] md: Don't clear MD_CLOSING when the raid is
 about to stop

On Wed, 17 Jan 2024 17:37:05 +0800
linan666@...weicloud.com wrote:

> From: Li Nan <linan122@...wei.com>
> 
> The raid should not be opened anymore when it is about to be stopped.
> However, other processes can open it again if the flag MD_CLOSING is
> cleared before exiting. From now on, this flag will not be cleared when
> the raid will be stopped.
> 
> Fixes: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called
> md_set_readonly or do_md_stop") Signed-off-by: Li Nan <linan122@...wei.com>
> ---
>  drivers/md/md.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 9bdd57324c37..4bf821b89415 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -6254,7 +6254,15 @@ static void md_clean(struct mddev *mddev)
>  	mddev->persistent = 0;
>  	mddev->level = LEVEL_NONE;
>  	mddev->clevel[0] = 0;
> -	mddev->flags = 0;
> +	/*
> +	 * Don't clear MD_CLOSING, or mddev can be opened again.
> +	 * 'hold_active != 0' means mddev is still in the creation
> +	 * process and will be used later.
> +	 */
> +	if (mddev->hold_active)
> +		mddev->flags = 0;
> +	else
> +		mddev->flags &= BIT_ULL_MASK(MD_CLOSING);
>  	mddev->sb_flags = 0;
>  	mddev->ro = MD_RDWR;
>  	mddev->metadata_type[0] = 0;
> @@ -7728,6 +7736,12 @@ static int md_ioctl(struct block_device *bdev,
> blk_mode_t mode, 
>  	case STOP_ARRAY:
>  		err = do_md_stop(mddev, 0, bdev);
> +		if (!err)
> +			/*
> +			 * mddev has been stopped, keep flag the
> +			 * MD_CLOSING to prevent reuse.
> +			 */
> +			did_set_md_closing = false;

Hello Nan,
The meaning of the "did_set_md_closing" is to notify that MD_CLOSING was set in
this function, to know how to behave on error.
You gave it another meaning "Do not clear MD_CLOSING because we want it to stay"
Please consider how to solve this confusion. I see the comment you added but I
think we can have this solved better, maybe just name it as "clear_md_closing"?

Anyway it looks acceptable to me:
Acked-by: Mariusz Tkaczyk <mariusz.tkaczyk@...ux.intel.com>

Thanks,
Mariusz