vfs: force reval of target when following LAST_BIND symlinks (try #7)

	return dentry;

}

/*

 * force_reval_path - force revalidation of a dentry

 *

 * In some situations the path walking code will trust dentries without

 * revalidating them. This causes problems for filesystems that depend on

 * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set

 * (which indicates that it's possible for the dentry to go stale), force

 * a d_revalidate call before proceeding.

 *

 * Returns 0 if the revalidation was successful. If the revalidation fails,

 * either return the error returned by d_revalidate or -ESTALE if the

 * revalidation it just returned 0. If d_revalidate returns 0, we attempt to

 * invalidate the dentry. It's up to the caller to handle putting references

 * to the path if necessary.

 */

static int

force_reval_path(struct path *path, struct nameidata *nd)

{

	int status;

	struct dentry *dentry = path->dentry;

	/*

	 * only check on filesystems where it's possible for the dentry to

	 * become stale. It's assumed that if this flag is set then the

	 * d_revalidate op will also be defined.

	 */

	if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))

		return 0;

	status = dentry->d_op->d_revalidate(dentry, nd);

	if (status > 0)

		return 0;

	if (!status) {

		d_invalidate(dentry);

		status = -ESTALE;

	}

	return status;

}

/*

 * Short-cut version of permission(), for calling on directories

 * during pathname resolution.  Combines parts of permission()

		error = 0;

		if (s)

			error = __vfs_follow_link(nd, s);

		else if (nd->last_type == LAST_BIND) {

			error = force_reval_path(&nd->path, nd);

			if (error)

				path_put(&nd->path);

		}

		if (dentry->d_inode->i_op->put_link)

			dentry->d_inode->i_op->put_link(dentry, nd, cookie);

	}