From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (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 2A813A55; Wed, 28 May 2025 22:37:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748471861; cv=none; b=DOkTC4/h2VRppetvypvXbboBjLFg3KxecuXHh82kleKcUZvHJCdvPzUGs8jP0s8H9gRz1iWJoH8NDxiPaqClG4HB0rDM1wyHLBQx1OiGJHyHlL8CFLedYiqGu3qYIY3OcB0GW6PfFPYCma7S3aVGfnMteZqvaCbLNT+Q6E7UXFk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748471861; c=relaxed/simple; bh=xmQYotvaywYw/vHqjd6pEK8c6S0COqcKSf9drJjX+fM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oa4Sf8kRgEzPggbpm7MkzRbI0o68aebeg0eej/svEHsIDgHKWBS9O6d4UNDq+Rprc6md0JnPwRaPnmIR6bx8yAvdSyKqF4qS2O3SVFEfoy97xe/grB5IgpuChx2nhGipbuMwvgkmG8pIp00Pvm8PFABmQFojgD5zEraslWk+/NI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=Oc1KfxHL; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="Oc1KfxHL" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=edzQ9Ntr0wuVhkuHEzdr0zVPfW1RopJDB/sRSx9qXAM=; b=Oc1KfxHLpJW18hybyOdvys7lIy PU3NAaBnJHp5q9PyKXkKq/Atvrsz0Nktq911yn3TkNtW+xcCIHleANherqdXBd071IM+KOXBlFeEo Z+AJQFiSn3zKCvHth80+46fyZcgBdhuZIEGiSS1bSZ2bjreUTiGLyovVoIK/UV30kv6myOYUuFyTF KpL4+VHL8rWFPHn3krf1gRILl/KOHKEglH9kIg9xgMFpvMIR43h3iFgvkCDUhXceWDbqXfsDhyDHF H5LRD+RZXi9lVVoLYCHtvHdVxLCgLbxKiNrwoXitahBzoyt7BCi3/pdNBHNQYIr5bUGhb2NgN4Hpp 2HiOdTkg==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uKPOn-0000000AGTU-00QN; Wed, 28 May 2025 22:37:25 +0000 Date: Wed, 28 May 2025 23:37:24 +0100 From: Al Viro To: Song Liu Cc: bpf@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@meta.com, andrii@kernel.org, eddyz87@gmail.com, ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, brauner@kernel.org, jack@suse.cz, kpsingh@kernel.org, mattbobrowski@google.com, amir73il@gmail.com, repnop@google.com, jlayton@kernel.org, josef@toxicpanda.com, mic@digikod.net, gnoack@google.com Subject: Re: [PATCH bpf-next 3/4] bpf: Introduce path iterator Message-ID: <20250528223724.GE2023217@ZenIV> References: <20250528222623.1373000-1-song@kernel.org> <20250528222623.1373000-4-song@kernel.org> Precedence: bulk X-Mailing-List: bpf@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: <20250528222623.1373000-4-song@kernel.org> Sender: Al Viro On Wed, May 28, 2025 at 03:26:22PM -0700, Song Liu wrote: > Introduce a path iterator, which reliably walk a struct path. No, it does not. If you have no external warranty that mount *and* dentry trees are stable, it's not reliable at all. And I'm extremely suspicious regarding the validity of anything that pokes around in mount trees. There is a very good reason struct mount is *not* visible in include/linux/*.h