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	id D680268CFE; Wed, 19 Aug 2026 07:46:50 +0200 (CEST)
Date: Wed, 19 Aug 2026 07:46:50 +0200
From: Christoph Hellwig <hch@lst.de>
To: Runyu Xiao <runyu.xiao@seu.edu.cn>
Cc: Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Keith Busch <kbusch@kernel.org>,
	Logan Gunthorpe <logang@deltatee.com>,
	linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org, Jianhao Xu <jianhao.xu@seu.edu.cn>
Subject: Re: [PATCH 1/2] nvmet: avoid recursive configfs open for
 file-backed namespaces
Message-ID: <20260819054650.GB32649@lst.de>
References: <20260817143714.1344255-1-runyu.xiao@seu.edu.cn> <20260817143714.1344255-2-runyu.xiao@seu.edu.cn>
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User-Agent: Mutt/1.5.17 (2007-11-01)

> +	ret = kern_path(ns->device_path, LOOKUP_FOLLOW, &path);
> +	if (ret) {
> +		pr_err("failed to open file %s: (%d)\n",
> +		       ns->device_path, ret);
> +		return ret;
> +	}
> +
> +	if (!strcmp(path.dentry->d_sb->s_type->name, "configfs")) {
> +		pr_err("configfs paths cannot back namespace %s\n",
> +		       ns->device_path);
> +		path_put(&path);
> +		return -EINVAL;
> +	}

String comparisons are a bit weird, checking the actual file_system_type
is a lot cheaper and more safe.  And please move this into a helper
in configfs as I bet there are tons of other users like this and they'd
benefit fro ma common helper.