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Message-ID: <4ccf5784-9e7f-6faf-a710-a97273ebd737@molgen.mpg.de>
Date:   Fri, 9 Sep 2022 06:53:34 +0200
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Subject: Re: [PATCH v2 2/3] md: Remove extra mddev_get() in md_seq_start()
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     Song Liu <song@kernel.org>, linux-kernel@vger.kernel.org,
        linux-raid@vger.kernel.org, Christoph Hellwig <hch@infradead.org>,
        Guoqing Jiang <guoqing.jiang@linux.dev>,
        Stephen Bates <sbates@raithlin.com>,
        Martin Oliveira <Martin.Oliveira@eideticom.com>,
        David Sloan <David.Sloan@eideticom.com>,
        Christoph Hellwig <hch@lst.de>
References: <20220908161516.4361-1-logang@deltatee.com>
 <20220908161516.4361-3-logang@deltatee.com>
Content-Language: en-US
From:   Paul Menzel <pmenzel@molgen.mpg.de>
In-Reply-To: <20220908161516.4361-3-logang@deltatee.com>
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Dear Logan,


Thank you for the updated series. One nit below, which could be 
corrected by the maintainer before applying.

Am 08.09.22 um 18:15 schrieb Logan Gunthorpe:
> A regression is seen where mddev devices stay permanently after they
> are stopped due to an elevated reference count.
> 
> This was tracked down to an extra mddev_get() in md_seq_start().
> 
> It only happened rarely because most of the time the md_seq_start()
> is called with a zero offset. The path with an extra mddev_get() only
> happens when it starts with a non-zero offset.
> 
> The commit noted below changed an mddev_get() to check its success
> but inadevrtantly left the original call in. Remove the extra call.

inadvertently

> Fixes: 12a6caf27324 ("md: only delete entries from all_mddevs when the disk is freed")
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Guoqing Jiang <Guoqing.jiang@linux.dev>
> ---
>   drivers/md/md.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index afaf36b2f6ab..9dc0175280b4 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8154,7 +8154,6 @@ static void *md_seq_start(struct seq_file *seq, loff_t *pos)
>   	list_for_each(tmp,&all_mddevs)
>   		if (!l--) {
>   			mddev = list_entry(tmp, struct mddev, all_mddevs);
> -			mddev_get(mddev);
>   			if (!mddev_get(mddev))
>   				continue;
>   			spin_unlock(&all_mddevs_lock);


Kind regards,

Paul