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 E000F2F6562 for ; Sun, 4 Jan 2026 07:40:37 +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=1767512440; cv=none; b=TdLjGYh7/bFqIn4cfpHDRIJ501291Az+RWJSfE6wlEC0PdmWEqkDew7HuhmyX2JHwKm9n7AKJOYuyzi7AVrlg7qEUWdxP39ztGs9yJ48sDlwxmU7SOQemF8+OFJM/+qU3aMQ2HlKESH+5/7iU2tIKJIeI8lqJkRLmOdLxy4VWuU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767512440; c=relaxed/simple; bh=NnVbZEuuf8hO5AW3rnr/wuAA6KiRkXMBzDkB/HM01RE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=F/M2TXXkLMgs2EzDnrCqBNJX6SAWIqPyL5GYPSC7QBdzfdm5JtP0VoqOrdsqHMJdKntBCYZg978XC6TDV0J36zNZjmbvEfYa97ZUl9OTUM7xyGD/XEC/B5iPhvShxToxuK6wprg57oAVCesU+5vsMJPB3FD7VrZe72JSgu8RI1k= 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=BCvNxspR; 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="BCvNxspR" 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=fGcDkVpKeFeVQZH8cINYDXBgZkNvfKnaiAYQryYaFBE=; b=BCvNxspR4yfHoNONaKGHIgwfhr hwpUTtKEzYxoMg7O7dPzC0r84c7jESXnDL2RfnqisE7p7phSRhi3ZkD15corRCMyFkIYrnP000PIe ZncrZy0RFf+/Azd0hu9c0hvTjC2viVl69hyW0h0M3T/uYVccs3s73Snh8F7nn+wMA7xJhePP5ez10 ouyprr0NL9GeJ3LVm8d1QNEft8h61Xm9dSgEYToUDL8m/G1pMGDffUe/N2AKOo1Vd9L1dAhmEhAOL R3G3UeDtRuzsPDs70atTq1fkz6YFot/LxaiDoO/A8lkc70ee3NrkR+2C3+RWxTRxoPCf0pr40cMZ6 3ml49R/g==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.99 #2 (Red Hat Linux)) id 1vcIkD-0000000D0F3-3RbC; Sun, 04 Jan 2026 07:41:45 +0000 Date: Sun, 4 Jan 2026 07:41:45 +0000 From: Al Viro To: Christian Brauner Cc: linux-fsdevel@vger.kernel.org, Jan Kara , Jeff Layton , Amir Goldstein , Lennart Poettering , Zbigniew =?utf-8?Q?J=C4=99drzejewski-Szmek?= , Josef Bacik Subject: Re: [PATCH 3/3] fs: add immutable rootfs Message-ID: <20260104074145.GJ1712166@ZenIV> References: <20260102-work-immutable-rootfs-v1-0-f2073b2d1602@kernel.org> <20260102-work-immutable-rootfs-v1-3-f2073b2d1602@kernel.org> <20260104072743.GI1712166@ZenIV> 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: <20260104072743.GI1712166@ZenIV> Sender: Al Viro On Sun, Jan 04, 2026 at 07:27:43AM +0000, Al Viro wrote: > On Fri, Jan 02, 2026 at 03:36:24PM +0100, Christian Brauner wrote: > > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* Copyright (c) 2026 Christian Brauner */ > > +#include > > +#include > > +#include > > [snip] > > What does it give you compared to an empty ramfs? Or tmpfs, for that > matter... > > Why bother with a separate fs type? Make that "empty ramfs" and as soon as you've got the mount have mnt->mnt_root->d_inode->i_flags |= S_IMMUTABLE; done. No concurrent accesses at that point, no way to clear that flag for ramfs inodes afterwards and ramfs is always built in... What am I missing here?