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Date:   Thu, 15 Aug 2019 00:36:32 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Sascha Hauer <s.hauer@pengutronix.de>
Cc:     linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org,
        Jan Kara <jack@suse.com>, Richard Weinberger <richard@nod.at>,
        kernel@pengutronix.de
Subject: Re: [PATCH 05/11] quota: Allow to pass quotactl a mountpoint
Message-ID: <20190814233632.GW1131@ZenIV.linux.org.uk>
References: <20190814121834.13983-1-s.hauer@pengutronix.de>
 <20190814121834.13983-6-s.hauer@pengutronix.de>
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On Wed, Aug 14, 2019 at 02:18:28PM +0200, Sascha Hauer wrote:
> +/**
> + * reference_super - get a reference to a given superblock
> + * @sb: superblock to get the reference from
> + *
> + * Takes a reference to a superblock. Can be used as when the superblock
> + * is known and leaves it in a state as if get_super had been called.
> + */
> +void reference_super(struct super_block *sb)
> +{
> +	spin_lock(&sb_lock);
> +	sb->s_count++;
> +	spin_unlock(&sb_lock);
> +
> +	down_read(&sb->s_umount);
> +}
> +EXPORT_SYMBOL_GPL(reference_super);

NAK, for a plenty of reasons

1) introduction of EXPORT_SYMBOL_GPL garbage
2) aforementioned garbage on something that doesn't need to be exported
3) *way* too easily abused - get_super() is, at least, not tempting to
play with in random code.  This one is, and it's too low-level to
allow.