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 DA1E01A238E; Mon, 9 Dec 2024 13:46:57 +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=1733752019; cv=none; b=B/0WHGxxcMY3KYCxQOlIdXIU/VlQ6FLVtwq5wDbIPkTkTmQXD9qS1m0ruRpcJb4f19N9exHhAcpZPcGm/4teJ3OGyyN52DwLL+ykIi1gjt5CcxEJTQQDIUIcBqHUV47sj0Mcl9bxrTMXdw/FXr5cqZjXt7X5BSKLseP4gmcKqF8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733752019; c=relaxed/simple; bh=7YMcql3307lL7mtzM9GeKeg6x8rr1woEKBhM4L9q1YY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TJOhfmibDoOYeUuuF4eINXd5JtZZ2mkDKSMoN+l1pG1sszoH733hAjTH9oGSUqZVN2ILkcDTvxK9qaP8Tdjy0HLgFnREhycUcB0u+eVgsUhxdxQDnxVii6DBDpmWRex/H9H0XQz+fjVayk08gwDJeJo/26GqGpkftzsiZh/2IJA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=wKzci/M0; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="wKzci/M0" 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=w43T1I6/sKwJscxNGbfJG/M/ns6oG3NjgCwcsgsn5ec=; b=wKzci/M0+tJjPJMVBnZLPgTW6a gQ0H2/IbEZgQ212cFKxiI67Ey3pi4lT7duv3vIwB2y04YsEr92pdfx0aWKdU/4yVmOaqIFcpGH9Is EjIxHi64qjRFHLWwuCN5auy0pEWLWC+owNk1M+sCEg6d9tN3+CBnkshw+Q1lW6L/tHv/5SGJqXS4e zLwswz4JzBakMqKXAutVpypips45STjMrkTaTHpSmMVPuenOe3ZPca/u3u/7sFNvRY0Kf1TzRli1q cYqXnnOJBFkt8sAKVhLMp9H3ygZCfGRLtHe25KSjCx+n4dBlAajd1XZDTR7sBaSTOOq2hFU8Q6GRS nnV26qqA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tKe6C-000000083to-3T6r; Mon, 09 Dec 2024 13:46:56 +0000 Date: Mon, 9 Dec 2024 05:46:56 -0800 From: Christoph Hellwig To: Amir Goldstein Cc: Christoph Hellwig , "Darrick J. Wong" , Christian Brauner , Jeff Layton , Erin Shepherd , Chuck Lever , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, stable , Greg KH , Jens Axboe , Shaohua Li Subject: Re: [PATCH 0/4] exportfs: add flag to allow marking export operations as only supporting file handles Message-ID: References: <20241201-work-exportfs-v1-0-b850dda4502a@kernel.org> <20241206160358.GC7820@frogsfrogsfrogs> 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=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Dec 09, 2024 at 09:58:58AM +0100, Amir Goldstein wrote: > To be clear, exporting pidfs or internal shmem via an anonymous fd is > probably not possible with existing userspace tools, but with all the new > mount_fd and magic link apis, I can never be sure what can be made possible > to achieve when the user holds an anonymous fd. > > The thinking behind adding the EXPORT_OP_LOCAL_FILE_HANDLE flag > was that when kernfs/cgroups was added exportfs support with commit > aa8188253474 ("kernfs: add exportfs operations"), there was no intention > to export cgroupfs over nfs, only local to uses, but that was never enforced, > so we thought it would be good to add this restriction and backport it to > stable kernels. Can you please explain what the problem with exporting these file systems over NFS is? Yes, it's not going to be very useful. But what is actually problematic about it? Any why is it not problematic with a userland nfs server? We really need to settle that argumet before deciding a flag name or polarity.