From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.208.51 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794235912; b=dzgUaI/j/LI32nrJE1JQZFXAevXEr5YclBFAM71IIdaK9POrRlJoJNchnrPQO0cgQ0XL ltAAUio1E2jBWORqKtYaxymHaZ4nkMQmgqOvkrPsg7xf35NyD5k4fKffAWmpyu6qehehn BMzmJjMFAWoAVdGgvIWt6Sr5E5Wy1C3fjoadOB6BXKpJsk0YSQ5zQtOn7g3ViVqls9SQo tUJhJ2JtgMiUGJw0tWh8PYhe2vjqbLwDOt7rzbsqSv7KvCSzsqlSi5mMLDPOblTis7kRa /dYeBKGcc2puLwmpMbhfvU75QDEVmaB/Vsasa7gd7TZXWwyOPDOAf91qfNBWgq+m7VA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794235912; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:Content-Transfer-Encoding: In-Reply-To; bh=J/ON+kd3JZ2PEUk7mTIiSkX+r3bemsj8teqmqV8x0KE=; b=p0wQgwYZD1HEjUyy7XUY5i9oXwWKhghMSum185J/swnpxZL091OvM0TCjvSeRJMn+bEH WzAPhqHeE8AWO8tscbo/rADa/PKhGxiP4c0xJg+nD8m284xookWFr8vWvpC+LW6T4bisy xcafjFGg+am0bYbnPC8jIen0qbZajdkG4JjXwTCiBFDN2Fnh20bH8GjCipDXI51L72GOm WnZfxnitNDO3wb0p4E7F9vuLgC/sRcz2xvH85ef7aAjn53eRlaLLHt0UgTeBGXoeTWhfC PGS1spimHQ/ZmrWYmidctiIj72EPwGPfmj9yw8+yvWivW97LEWV+rf4WO3exZvclm0A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=PkleYFAc; arc=none smtp.remote-ip=209.85.208.51 Received: from mail-ed1-f51.google.com (mail-ed1-f51.google.com [209.85.208.51]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 17F72606A31C for ; Mon, 9 Nov 2026 14:51:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 17F72606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=PkleYFAc Received: by mail-ed1-f51.google.com with SMTP id 4fb4d7f45d1cf-6b633ddfad6so1252971a12.3 for ; Mon, 09 Nov 2026 06:51:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1794235910; x=1794840710; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :content-type:mime-version:references:message-id:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to:content-type; bh=J/ON+kd3JZ2PEUk7mTIiSkX+r3bemsj8teqmqV8x0KE=; b=PkleYFAc+0BvCXsJXVq3M/zBPc+eyFBW6hC4WYb2ML24PLhITX2DmlX3mLQNASXS1N nc5jJqreb/r14U3fqpOlQvSvR1Nb/tmPlVv7VniorSqIYqocbkm6ZOIU838NH2hN2oZ4 SFgYWXIBafbDJB9SqchXjKumyuKVdXMex6/5jmglbujr/AlM7HnnXm96IdSthgrZkDXn GGaQ3sgNTyk9FHxWLk2lX2BQm5sQ7F4wQMv9FqGaKlP8K2jWsptRBQ4YkAqwSzBlFg+4 PcChdGXGfFcegdYid+AA+XUylPI7d2UcVlQokEUL6HsSjvO3geAVocKtk8nAnG7xU0kU 354A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794235910; x=1794840710; h=in-reply-to:content-transfer-encoding:content-disposition :content-type:mime-version:references:message-id:subject:cc:to:from :date:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=J/ON+kd3JZ2PEUk7mTIiSkX+r3bemsj8teqmqV8x0KE=; b=NtJlSSSomLetiLE4T3oZ8ILOZTyPIv7oz7zwhzniGHP7AlulTg7sc3YlgWZB83Sebl TG2AbuB2xeE7P261Eo8gA9AVXPlzx34C5WASSd4STVg4qn+Sqbg9jejgJkznOz4wAUaK BJNsMFGs6soc5rAh/buEBtrbFjnjW14ugjyFL8kdX/YRVwlQmzyPeKTRmjk66pz2FZcd 4i23v9aS3fsgqXrSf69d2csUwRSf5Hk2ghKbgEaCka6kPoxOkLwbXosUxuUslIBJt7vc Wp8Z80d/mHezJIU4VyI33dw8N88sbmHETRIKI4tdQ7/v31/dgdDVcTVuwEAJw/HfUoQK UT3A== X-Forwarded-Encrypted: i=1; AL+hErEz7PUJFFIpkNupH1Y1pxwNRqBv7AxhzLJrBR7JGLO9i3ZbTm2IA/cI3l0hlsebyjpHhhAP6spxNUf4S9da@vger.kernel.org X-Gm-Message-State: APuU4Z/wNGj+kQDj31nhfya9/k3PflOk749KhX11ij1TKIjVe/B1GJ9B blloA5HMg03W3Ji1jH5jHhOagCfcBDudd7yW6UBOPWfhnQyh75h5H6dW X-Gm-Gg: AYBFou32yPpc3VIQ5qg4YlOVLFuJlA7/vOFtyGCOJq3bTK5nfVaCB1LYLdl0BPtJZmk COOyYvdGdNwLq4aom573Ayq5nmi6EyWmaTQSo2yoDHhcGO/vRGn4d7f99RZdzcSXuYTZkjoN+jH yS8BS+V3gVKGSieZMWiPkMfhhj1usujPiUmMD7XjII1DgpIOtquCVQfrWtDPtQkEOyGsUsLqKxp OciSyt036F9WgVbjBJnFuoJE++l3dmfiSP98+jjq42entlEPlSKd1s6rHwE5BSA9UJQ1eeDt9PA H2xaZplMn9scXxwqaVqg5eqnJQIZyjw6GLejcMRTqG7NDnnbiOD1+I7+0sQ2dot7RSzyLqqut3B kUugxquotN228Q8ms+A4pUWIO095+G0clUj8proqBlLnRlalO6vXXWg6lEKtYd5rTuVkLCk+bwa UZjuMtUe542Lx1INt90PklyjcIo1MTfhbFLM750FF8ybkTHQlUubDjf0lkjedQe1o30BCdUyaIh tOkd42H/q34LszQ/5iuk0kD+arDDaCc+X34IlAkYrw4I4HBxlVH8CxDCvqCAdFVUXWkjXTHK7hp EXRC0fKXbLkiTJVv7FpYj8f1GhbxjfQ+w3Aa2wng3p8g8B30DSkHkkIkAIffDvL+Gh71/fwnefl zYDTyH+Jq8kI= X-Received: by 2002:a05:6402:528f:b0:6b5:660b:70dd with SMTP id 4fb4d7f45d1cf-6b722484c1fmr3165155a12.21.1794235910318; Mon, 09 Nov 2026 06:51:50 -0800 (PST) Received: from localhost (178-84-201-199.dynamic.upc.nl. [178.84.201.199]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6b721eedfd7sm1603106a12.31.2026.11.09.06.51.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 06:51:49 -0800 (PST) Date: Mon, 9 Nov 2026 15:51:49 +0100 From: Amir Goldstein To: =?iso-8859-1?B?Suly6W15?= Jean Cc: Christian Brauner , miklos@szeredi.hu, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/3] ovl: disable nfs_export for same-sb lower layers with different idmaps Message-ID: References: <20260920203239.2876221-2-Jeremy.Jean@oss.cyber.gouv.fr> <20260920203239.2876221-3-Jeremy.Jean@oss.cyber.gouv.fr> <20260925-server-hager-riskieren-06116eded213@brauner> <5e8dff576ead72fa502b7cd38889e780@oss.cyber.gouv.fr> X-Mailing-List: linux-unionfs@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5e8dff576ead72fa502b7cd38889e780@oss.cyber.gouv.fr> On Sun, Nov 08, 2026 at 08:12:49PM +0100, Jérémy Jean wrote: > On 2026-09-25 16:17, Amir Goldstein wrote: > > On Fri, Sep 25, 2026 at 3:51 PM Christian Brauner > > wrote: > > > > > > On Mon, Sep 21, 2026 at 10:10:28AM +0200, Amir Goldstein wrote: > > > > On Sun, Sep 20, 2026 at 10:33 PM Jérémy Jean > > > > wrote: > > > > > > > > > > Overlay file handles identify a backing filesystem, but not the lower > > > > > mount used to decode it. If lower layers share a superblock and use > > > > > different idmaps, a file handle can decode through the wrong layer and > > > > > initialize the overlay inode with the wrong owner. > > > > > > > > > > Track the first lower idmap seen for each ovl_sb and disable nfs_export > > > > > when another lower layer on the same backing superblock uses a different > > > > > idmap. Keep index enabled: copy up starts from the overlay dentry selected > > > > > by lookup and does not need to decode a lower file handle through another > > > > > layer. > > > > > > > > > > Fixes: bc70682a497c ("ovl: support idmapped layers") > > > > > Assisted-by: Codex:gpt-5 > > > > > Signed-off-by: Jérémy Jean > > > > > --- ... > > > > > +/* > > > > > + * Lower file handles identify a lower fs, but not the mount whose idmap was > > > > > + * used to decode them. Remember the first lower idmap seen for each fs so > > > > > + * decodable export handles can be disabled if another one appears. > > > > > > I find this behavior counterintuitive. Shouldn't we just fail the > > > mount then? > > > > I would love to fail the mount if you confirm that setting up an ovl > > with several > > lower layers some on the same fs with different idmap, is a non-feature. > > > > I don't know can't /home/amir and /home/brauner be on the same fs with > > different idmapping? > > > > Could it ever make sense to compose an overlay from two such > > directories? > > If not then I would gladly remove this setup from the test matrix. > > > > Thanks, > > Amir. > > Hello, > > I'm digging this up: should I investigate to prepare a new version that > simply fails the mount? Yes, please. Thanks, Amir.