Re: [PATCH 8/9] md: only delete entries from all_mddevs when the disk is freed

From: Guoqing Jiang <guoqing.jiang@linux.dev>
To: Christoph Hellwig <hch@lst.de>, Song Liu <song@kernel.org>
Cc: Logan Gunthorpe <logang@deltatee.com>,
	linux-raid@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [PATCH 8/9] md: only delete entries from all_mddevs when the disk is freed
Date: Fri, 15 Jul 2022 17:03:53 +0800	[thread overview]
Message-ID: <0117b8d7-b318-df06-4ada-2d4eaefea68a@linux.dev> (raw)
In-Reply-To: <20220713113125.2232975-9-hch@lst.de>

On 7/13/22 7:31 PM, Christoph Hellwig wrote:
> This ensures device names don't get prematurely reused.*Instead*  add a
> deleted flag to skip already deleted devices in mddev_get and other
> places that only want to see live mddevs.

The patch actually adds a deleted member to struct mddev , so the 
"Instead" here
is at least confusing to me.

> Reported-by; Logan Gunthorpe<logang@deltatee.com>
> Signed-off-by: Christoph Hellwig<hch@lst.de>
> ---
>   drivers/md/md.c | 56 +++++++++++++++++++++++++++++++++----------------
>   drivers/md/md.h |  1 +
>   2 files changed, 39 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index df99a16892bce..f3ff61e540ee0 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -625,6 +625,10 @@ EXPORT_SYMBOL(md_flush_request);
>   
>   static inline struct mddev *mddev_get(struct mddev *mddev)
>   {
> +	lockdep_assert_held(&all_mddevs_lock);
> +
> +	if (mddev->deleted)
> +		return NULL;
>   	atomic_inc(&mddev->active);

...

> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 1a85dbe78a71c..bc870e1f1e8c2 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -503,6 +503,7 @@ struct mddev {
>   
>   	atomic_t			max_corr_read_errors; /* max read retries */
>   	struct list_head		all_mddevs;
> +	bool				deleted;
>   
>   	const struct attribute_group	*to_remove;

Thanks,
Guoqing