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 0D9BE6BFCE; Wed, 21 Jan 2026 09:17:48 +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=1768987073; cv=none; b=FLjYUmlYMcxXoOxDG5TGCetkkDY/tIjnE2AB9jBPOkiQNiDxc2X0qfMny8ldiGaI/TOW98f3bzioMD7c16gsheBJnk4rTsV8xei1fuvqe8+ZSNY6+QuHFfZET5S6OvG5vSHcrNlOWUexW5V5PU0uwjzITOU0zy59iFTuz1rVgqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768987073; c=relaxed/simple; bh=zw5vJ+ZC4/w8uoZ94zfN7TTnawq76kDFNZ0VoHKbhx0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JwnhuGVwy3Zi/UA+sS/mbpp5Y2RU8yIwuPCr8FrUKXOxkHq5Vag8DaYDfrXUxOmD8dt1GpKRkEKFtXhntXWuvscYbyNqBk0kdaTRSv28MmW6H1vgQVVSsZKgpFm0t7GIXFTNhTxa+UCJgLcLa9V6yDJGfcaeleBc8m2ET4tyoKg= 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=dL4371OF; 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="dL4371OF" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=QMRVjotEayLOv8XTxaxuE0M55enKBYtQeaeNcrACLfc=; b=dL4371OFHyaeDBmxzj7GOgrMx3 3K3xbidZALqODJsAS8whqERF7Cf9V7Fo7hOwrsqaJ52l4+3LZ3NOo6ToaJTvHKZRqcoXdeIkI5i2Y /IGCwCDyqZvkKB3vxuq/jXLgMBASekbT7z2m5uG7UV6Z1vT7LxO5FNkuYsqXQ65ggC8pblORDhMxn g88h/3uSdhW32hsFMLKV41gZ2EzUh0QwXmfBFzhtXFBCIM8iZiBvymXdqRapwUqUsREyNCfkJfKnN emlY1xCH7+a+KdQVe/KemipvA79Ca3KD2ZAnJ6dAOXDUOz1nqP1FfvsKk+szaZfJ4qnOmyQQriS0o bmhS62CA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1viUKw-00000005AiH-18Yv; Wed, 21 Jan 2026 09:17:14 +0000 Date: Wed, 21 Jan 2026 01:17:14 -0800 From: Christoph Hellwig To: Jan Kara Cc: Christoph Hellwig , Jeff Layton , Christian Brauner , Alexander Viro , Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Amir Goldstein , Hugh Dickins , Baolin Wang , Andrew Morton , Theodore Ts'o , Andreas Dilger , Jan Kara , Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Sandeep Dhavale , Hongbo Li , Chunhai Guo , Carlos Maiolino , Ilya Dryomov , Alex Markuze , Viacheslav Dubeyko , Chris Mason , David Sterba , Luis de Bethencourt , Salah Triki , Phillip Lougher , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Bharath SM , Miklos Szeredi , Mike Marshall , Martin Brandenburg , Mark Fasheh , Joel Becker , Joseph Qi , Konstantin Komarov , Ryusuke Konishi , Trond Myklebust , Anna Schumaker , Dave Kleikamp , David Woodhouse , Richard Weinberger , Andreas Gruenbacher , OGAWA Hirofumi , Jaegeuk Kim , Jonathan Corbet , David Laight , Dave Chinner , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-xfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-unionfs@vger.kernel.org, devel@lists.orangefs.org, ocfs2-devel@lists.linux.dev, ntfs3@lists.linux.dev, linux-nilfs@vger.kernel.org, jfs-discussion@lists.sourceforge.net, linux-mtd@lists.infradead.org, gfs2@lists.linux.dev, linux-f2fs-devel@lists.sourceforge.net, linux-doc@vger.kernel.org, steve@digidescorp.com Subject: Re: [PATCH v2 02/31] exportfs: add new EXPORT_OP_STABLE_HANDLES flag Message-ID: References: <20260119-exportfs-nfsd-v2-0-d93368f903bd@kernel.org> <20260119-exportfs-nfsd-v2-2-d93368f903bd@kernel.org> <56fr33ju43h6zzp6jrzrkyfag6r3jz6wpnk45oe5byy6fqyvti@d43hgikfuk7t> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56fr33ju43h6zzp6jrzrkyfag6r3jz6wpnk45oe5byy6fqyvti@d43hgikfuk7t> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Jan 20, 2026 at 09:40:07AM +0100, Jan Kara wrote: > (with explanations before I couldn't quite see the difference between shmem > and kernfs). I'd note that fat or shmem (which are both exportable) > satisfy this only with reasonably high probability as they use > get_random_u32() for initializing their i_generation but I guess it's as > good as it gets for them. For tmpfs random generations are as good as it gets, in fact that's what XFS starts with when allocating new inode clusters (which could have previous been used for for inodes as well). fat on the other hand looks broken, as it also set a new generation when reading inodes from disk. So I don't think fat should be nfs exportable, even if the export ops predate other uses.