From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6314E37C912; Fri, 10 Jul 2026 05:34:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783661682; cv=none; b=uYVENOGxoVxoNWYKuYkcSakDIdeJEOndCzwbDl6HgSiE8Prk8pMxG/v8LYFPTy8jdHfyjfavhgIPSyUZn5jarrwhn7y0II5Giw1FCKmqIr7Nrx9SgKeZjXMecNBZGZcgpJM30BwXInIKeuql6jTk9+ghaNl31mlg3tdgaLKRVhY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783661682; c=relaxed/simple; bh=vCKqSO7FcPjO/fbcdFdGcfwyoGSC7wnRYM3eRRKXJbc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ri9wm8Br58Bsb4Qm0NB6O3WwXxxjXV6Kb7u79pdhsAX9C0fxPIPHsK8UfKLeE6md041UN7co4mKaQstPf3ba8LYWYzIKQRtrKD2fS9dbRnOZc8S+VZ6dUc+wsHM0DISHsAteSpLqCs4tjTgsRIrO7We+y4DgRtYoTurNRjgC4L0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=nE6MzMsB; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nE6MzMsB" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=2qfaKsY0c7jqCLpRus99rlIbzzgsY1Pbki0/Md4m9/Q=; b=nE6MzMsB3q2jNhkuVWarAeuKC8 RvRHuGY/0VKT0iXC13wSN78/YnBtLqEUIEEz1fCaq84+v7xn9bofN4dc6rrgAiyf1oRPvH1DJ3duF HF1iKztHy9ETtw6q8TWTPYfOQobXKKG7EGQtFrLlERqZc4XJvQLA6RkMLf2Nl0yW2Vghsu2a5Qn9F 6iC9AnlnJdUFX6lXRxpm/5ez8XppMb4q0+KLQoZYwAAmbQdNxo2quP3l6JhT64RGsG87wPxzKZiFo gA27xUMUPnGoGhoapY3+ZK8ztFewInmM8xZ9zBFRiIagJXBhTH8PUAMX15iVq8aGUsm5lNgO5z5tv p+fW7Hfg==; Received: from hch by bombadil.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wi3sn-00000004Cmh-08aN; Fri, 10 Jul 2026 05:34:41 +0000 Date: Thu, 9 Jul 2026 22:34:41 -0700 From: Christoph Hellwig To: Amir Goldstein Cc: Christian Brauner , Miklos Szeredi , Zorro Lang , linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, fstests@vger.kernel.org Subject: Re: [PATCH 2/2] src/vfs: skip whiteout-device fixtures on overlayfs Message-ID: References: <20260615-overlay-idmapped-vfstest-v1-0-c6b3b2228092@kernel.org> <20260615-overlay-idmapped-vfstest-v1-2-c6b3b2228092@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Jun 15, 2026 at 08:03:02PM +0200, Amir Goldstein wrote: > On Mon, Jun 15, 2026 at 5:33 PM Christian Brauner wrote: > > > > The idmapped mount tests create a whiteout device, > > mknod(S_IFCHR, makedev(0, 0)), as a fixture: a whiteout device is the > > only character device an unprivileged caller may create, since it is > > exempt from the CAP_MKNOD check. overlayfs reserves a 0:0 character > > device as its on-disk whiteout marker, so ovl_mknod() returns -EPERM > > and the fixture cannot be created, failing generic/633, generic/696 and > > generic/697 on overlayfs. > > > > Add an is_overlayfs() helper and skip the whiteout-device fixtures and > > the checks that depend on them on overlayfs. The makedev(5, 1) > > "creation must fail" probes are unaffected and keep running. No-op on > > every other filesystem. > > I have no strong objection to this patch but there was actually a request to > support makedev(0, 0) in overlayfs for creating overlayfs on an overlayfs root, > so perhaps it would be better to probe for makedev(0, 0) by fs owner instead > of the is_overlayfs() check. Where do we stand on this?