Date: Mon, 7 Dec 2015 10:39:11 -0500
From: Tejun Heo <tj@kernel.org>
To: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: serge@hallyn.com, linux-kernel@vger.kernel.org, adityakali@google.com,
        linux-api@vger.kernel.org, containers@lists.linux-foundation.org,
        cgroups@vger.kernel.org, lxc-devel@lists.linuxcontainers.org,
        akpm@linux-foundation.org, ebiederm@xmission.com
Subject: Re: [PATCH 7/8] cgroup: mount cgroupns-root when inside non-init
 cgroupns
Message-ID: <20151207153911.GF9175@mtj.duckdns.org>
References: <20151130150938.GF3535@mtj.duckdns.org>
 <20151201040704.GA31067@mail.hallyn.com>
 <20151201164649.GD12922@mtj.duckdns.org>
 <20151201215853.GA9153@mail.hallyn.com>
 <20151202165312.GB19878@mtj.duckdns.org>
 <20151202165637.GA20840@mail.hallyn.com>
 <20151202165839.GD19878@mtj.duckdns.org>
 <20151202170239.GA21009@mail.hallyn.com>
 <20151202170551.GE19878@mtj.duckdns.org>
 <20151203224706.GA19971@mail.hallyn.com>
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Hello, Serge.

On Thu, Dec 03, 2015 at 04:47:06PM -0600, Serge E. Hallyn wrote:
...
> +	dentry = dget(sb->s_root);
> +	if (!kn->parent) // this is the root
> +		return dentry;
> +
> +	knparent = find_kn_ancestor_below(kn, NULL);
> +	BUG_ON(!knparent);

Doing WARN_ON() and returning failure is better, I think.  Failing ns
mount is an okay failure mode and a lot better than crashing the
system.  Also, how about find_next_ancestor() for the name of the
function?

> +	do {
> +		struct dentry *dtmp;
> +		struct kernfs_node *kntmp;
> +
> +		if (kn == knparent)
> +			return dentry;
> +		kntmp = find_kn_ancestor_below(kn, knparent);
> +		BUG_ON(!kntmp);
> +		dtmp = lookup_one_len(kntmp->name, dentry, strlen(kntmp->name));
> +		dput(dentry);
> +		if (IS_ERR(dtmp))
> +			return dtmp;
> +		knparent = kntmp;
> +		dentry = dtmp;
> +	} while (1);

Other than the nitpicks, looks good to me.

Thanks.

-- 
tejun
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