From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 BD9C73A7DFA; Tue, 20 Jan 2026 07:32:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768894346; cv=none; b=tvUtjqtfggLBpPNvZ6yq8NX1MOut5PXU4yiG5XLpPv5S+13TwIhiZieE+ZlQg8jGdIc6Mi9tIQ4cbLU/OGH0wedPCxWces75MkJ+m1hlArl2aV21Wppo+KxtFrfcXeBiuWgPAggM8WmUQC3WME18iB7MgjPKZXtGoqp0iPBbqI4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768894346; c=relaxed/simple; bh=UcjeCV1pmWq68UG6mKTvuW3ZSkrfs3Ahq6enbyDbanU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZTcqU0oiStujaoRS45dtnZb209OuUr9GNDOzb9YVYFH9+Mv45kK0se8W49cI+BdATsQHIFO2IjlfZCtO/1nKcVuBB02JXckXXg64nBGgHY/j51Mv8sX4kCtn0ZojY3Hdhu3QIawuiV7vEYMMQrscujTBHJ3B3MkvFhhO/6UONdc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id B21F5227AA8; Tue, 20 Jan 2026 08:32:18 +0100 (CET) Date: Tue, 20 Jan 2026 08:32:18 +0100 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Eric Biggers , Christoph Hellwig , Andrey Albershteyn , Matthew Wilcox , fsverity@lists.linux.dev, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, aalbersh@kernel.org, david@fromorbit.com, tytso@mit.edu, linux-ext4@vger.kernel.org, jaegeuk@kernel.org, chao@kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: fsverity metadata offset, was: Re: [PATCH v2 0/23] fs-verity support for XFS with post EOF merkle tree Message-ID: <20260120073218.GA6757@lst.de> References: <20260114061536.GG15551@frogsfrogsfrogs> <5z5r6jizgxqz5axvzwbdmtkadehgdf7semqy2oxsfytmzzu6ik@zfvhexcp3fz2> <6r24wj3o3gctl3vz4n3tdrfjx5ftkybdjmmye2hejdcdl6qseh@c2yvpd5d4ocf> <20260119063349.GA643@lst.de> <20260119193242.GB13800@sol> <20260119195816.GA15583@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: <20260119195816.GA15583@frogsfrogsfrogs> User-Agent: Mutt/1.5.17 (2007-11-01) On Mon, Jan 19, 2026 at 11:58:16AM -0800, Darrick J. Wong wrote: > > > a) not all architectures are reasonable. As Darrick pointed out > > > hexagon seems to support page size up to 1MiB. While I don't know > > > if they exist in real life, powerpc supports up to 256kiB pages, > > > and I know they are used for real in various embedded settings > > They *did* way back in the day, I worked with some seekrit PPC440s early > in my career. I don't know that any of them still exist, but the code > is still there... Sorry, I meant I don't really know how real the hexagon large page sizes are. I know about the ppcs one personally, too. > > If we do need to fix this, there are a couple things we could consider > > doing without changing the on-disk format in ext4 or f2fs: putting the > > data in the page cache at a different offset than it exists on-disk, or > > using "small" pages for EOF specifically. > > I'd leave the ondisk offset as-is, but change the pagecache offset to > roundup(i_size_read(), mapping_max_folio_size_supported()) just to keep > file data and fsverity metadata completely separate. Can we find a way to do that in common code and make ext4 and f2fs do the same?