On Wed, Dec 07, 2011 at 01:37:20AM +0000, Al Viro wrote:
> +	if (path->mnt->mnt_flags & MNT_INTERNAL) {
> +		/* it's not mounted anywhere */
> +		res = dentry_path(path->dentry, buf, buflen);
> +		*name = res;
> +		if (IS_ERR(res)) {
> +			*name = buf;
> +			return PTR_ERR(res);
> +		}
> +		if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
> +		    strncmp(*name, "/sys/", 5) == 0) {
> +			/* TODO: convert over to using a per namespace
> +			 * control instead of hard coded /proc
> +			 */
> +			return prepend(name, *name - buf, "/proc", 5);


Incidentally, why only /proc/sys?  For one thing, we won't be accessing
anything else on internal vfsmount of proc, so strncmp() part looks
wrong; for another, if some code starts doing that, why would acting
as if it was on normally mounted /proc be the wrong thing?  John?