From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 1C90D39E6E3; Wed, 14 Jan 2026 16:17:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768407475; cv=none; b=YY2PiJVTFvacqy44wq2FsY0rhcZURWf/Afh9utYFC/+F90mybXVwsZqyOSWiLwQ4sprkVdei+iNlJrS2n4L6Oabr6UnwUhMe0keXB2VHdvMznZRfn1b8kgSMrEwazA1gy2TXsXARKjI5HAWbTXxJ+3e4j/GyG7+LUKSMENNvmqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768407475; c=relaxed/simple; bh=avV6DdjDrtuFKREDh7dX8ULQNvaPCX6uL3Qy8HX2D5U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=d6jvvkoJbOBNsKQ26q8r3gmP58ljqyweB6jd2XWoPHLssNiHblcow48rPYT84kXwe4zkjZP58MMc1d/78H301jq6EBwkr2g4GAhoFnKog2bebEfeW6VSXbGyPW0P4BfxqUp113/jviE1XOwkUdMqKoizB1CLm607U4GBjPUHPVE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=OcsDdENr; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="OcsDdENr" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=HpQaoCUPT6wdxz4f7lIznu8aR6PeVr63P5GrMsQT2F8=; b=OcsDdENrSHsJ/1ut8FlIWKp2QS C+gkAkCbSozPUltRTogIib69+Q5pTZgaYnmchsaNUB1Y2ktTb6eGJQKJ6uSjGxrupnZqUHe18jucF 9BR8mgKVtOpjOzK0ycGaD/bdztc9CFSWKUesUYAgwOkM9egQvkw0yKhN/yKa4gLzBO+/LRkD1I+mX Epzc4LTzPUeXlCLromTD02rQ6ZFZuWT6JUDbf8XdGpOE6Zuz1QuI4QgW5jIur4uKYJFQ/OSJa7Hqs WnQjg2ZQjkVw1nYS7Io5VyF+6EFgfBHV0YXFO76+H80STX38GdWrtlWSuFEVkYdo1laJpaBKS88K9 XcCDdWDg==; Received: from [177.139.22.247] (helo=[192.168.15.100]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1vg3Yi-005Lm6-3R; Wed, 14 Jan 2026 17:17:24 +0100 Message-ID: <5334ebc6-ceee-4262-b477-6b161c5ca704@igalia.com> Date: Wed, 14 Jan 2026 13:17:15 -0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/3] ovl: Use real disk UUID for origin file handles To: Christoph Hellwig Cc: Chuck Lever , Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Carlos Maiolino , Amir Goldstein , Chris Mason , David Sterba , Miklos Szeredi , Christian Brauner , Alexander Viro , Jan Kara , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-unionfs@vger.kernel.org, kernel-dev@igalia.com References: <20260114-tonyk-get_disk_uuid-v1-0-e6a319e25d57@igalia.com> <20260114-tonyk-get_disk_uuid-v1-3-e6a319e25d57@igalia.com> <20260114062608.GB10805@lst.de> Content-Language: en-US From: =?UTF-8?Q?Andr=C3=A9_Almeida?= In-Reply-To: <20260114062608.GB10805@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Em 14/01/2026 03:26, Christoph Hellwig escreveu: > On Wed, Jan 14, 2026 at 01:31:43AM -0300, André Almeida wrote: >> Some filesystem, like btrfs, supports mounting cloned images, but assign >> random UUIDs for them to avoid conflicts. This breaks overlayfs "index" >> check, given that every time the same image is mounted, it get's >> assigned a new UUID. > > ... and the fix is to not assign random uuid, but to assign a new uuid > to the cloned image that is persisted. That might need a new field > to distintguish the stamped into the format uuid from the visible > uuid like the xfs metauuid, but not hacks like this. > How can I create this non random and persisting UUID? I was thinking of doing some operation on top the original UUID, like a circular shift, some sort of rearrangement of the original value that we can always reproduce. Is this in the right direction do you think?