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 79E867346C; Mon, 27 May 2024 16:29:49 +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=1716827390; cv=none; b=TF0kIyuT6VFtpoqt90s35NUH8ohEeWnl26KaKgsy0It0HkhEe8qe6yOFQfiWUEwVIl+w53Z55av0LLToCLbu8WMxF5bXLA1fYzSnDHr7Zp6tnU9O/DU2PkEU2HkjOEU1jH8RqbNgJmPIgLC5utD470QhsI52CDRcfm/Z1h3ksow= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716827390; c=relaxed/simple; bh=aRoI7xtsmkM04Wifif6pMbPQqrT8YiNfoLqdNjPbItA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iz8Fs/816Sh6TFN564XctlfwBZ+/wfgJ+e/10Iq9TxXcfYVvU+F2EAFwIGZN1Mu5yWBo+icYw09HN6qsO/rNDBkMmpLFVrj2d/jSIuqRD8DjPTeK/j0nopoPiedNQAeQEq4SOJwxMTCwK93ESwWq+Qqa9AK/0mnuEbk4Pb2D57k= 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=kZyC3pE9; 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="kZyC3pE9" 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=Fe3M1WbTvAZeXMfbjuO8H7fTMStHiUlxRCcFwILoi+4=; b=kZyC3pE9swZXYLzz8yt3pUxTp2 /wqUOtShL76yRoPFsx9iwX/lZDip6D8a2JAF3nE6WkONLGSDL8ETYEQFkPopmvcDWZhvA9ZZXMSLr nWTrMyx6ITOcrcba+BCZnbjwJfK2EUrLu3yVC/BN7SweM9X3VBo037kruAppcin61/XenD2n4xu2q FGIWh5/RkrV++5MD10M9PWWOWML8/CzcNWqw6R4R/ls6LN7ENFYL9hlycOIlt1wnz3huLCC1T0SNp EhYrN47f6vcdD/SxCZMD76gOCQKv7RqTHY1WlVKJiy85arZ1tz4KMXJVApgY7W4AGPbbFLv7b+ps1 4m6EMf7g==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sBdEK-0000000FrSL-22Qr; Mon, 27 May 2024 16:29:48 +0000 Date: Mon, 27 May 2024 09:29:48 -0700 From: "hch@infradead.org" To: Trond Myklebust Cc: "hch@infradead.org" , "jack@suse.cz" , "chuck.lever@oracle.com" , "linux-api@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "brauner@kernel.org" , "linux-kernel@vger.kernel.org" , "alex.aring@gmail.com" , "cyphar@cyphar.com" , "viro@zeniv.linux.org.uk" , "jlayton@kernel.org" , "amir73il@gmail.com" , "linux-nfs@vger.kernel.org" Subject: Re: [PATCH RFC v2] fhandle: expose u64 mount id to name_to_handle_at(2) Message-ID: References: <20240523-exportfs-u64-mount-id-v2-1-f9f959f17eb1@cyphar.com> <30137c868039a3ae17f4ae74d07383099bfa4db8.camel@hammerspace.com> <86065f6a4f3d2f3d78f39e7a276a2d6e25bfbc9d.camel@hammerspace.com> 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: <86065f6a4f3d2f3d78f39e7a276a2d6e25bfbc9d.camel@hammerspace.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, May 27, 2024 at 03:38:40PM +0000, Trond Myklebust wrote: > > It > > does not matter what mount you use to access it. > > Sure. However if you are providing a path argument, then presumably you > need to know which file system (aka super_block) it eventually resolves > to. Except that you can't, at least not without running into potential races. The only way to fix a race vs unmount/remount is to include the fsid part in the kernel generated file handle. > > If your use case isn't NFS servers, then what use case are you > targeting, and how do you expect those applications to use this API? The main user of the open by handle syscalls seems to be fanotify magic.