From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (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 349623B3890 for ; Tue, 18 Aug 2026 03:06:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.9.28.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787022396; cv=none; b=LWh1VpgOIOtW31kdLqV16QDxMNwDbhI5BuN/GRuay3TQt3OYWCSIf/7MVmGikI0Ai92dj3ifhZCi59yH7Cq2ZPKyGihOKycCZf5W/GxyEGfAfDbBojdXpl3xCp9XYzV2WMFdbop34TU+slA46UC4TG+HpZOCpYKcX5w5wytRnZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787022396; c=relaxed/simple; bh=J95tn8ArPFqvw+hX8ol7vqADsEqXYVIBk38xwwA/rtA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eiCcutYTLFigCH1sNf1zdOZuLTxcm+DrD+geYcnEJdL+S50y6waG1ALEtijMDweOBVLwlrovajlHvx01cDcVLoixwtgCCO/pVTREhZ5C3KwlYEdrnqXjiGeO2f2XMhMXTn7A9qAbEafvXOY4N4T9x9fBECGz6BEhty9pi/M7bUg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b=ahWEq7rO; arc=none smtp.client-ip=18.9.28.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b="ahWEq7rO" Received: from macsyma.thunk.org (pool-173-48-113-153.bstnma.fios.verizon.net [173.48.113.153]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 67I35icI030207 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 17 Aug 2026 23:05:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1787022347; bh=wuBrA5KLkXsc0zKKVBww4QEECn7a2VCTcn2+mBjRbg0=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=ahWEq7rOLYCrAvyHmbaMoEHQHo5vj7NrssLLvk7Qo1U33bz1rGcoUqJvBzo0shmu7 b+nO2YelL25QWpUYE5xJcIV6WbYip5WhrbiBTLkTJvgmg4Yy0juEtPZ2C0qJqBmWzT IzGJCNi8UyxX7vTSqeqR58Tu5/KwraErnuGwc8rVu2DYnwTzGJ82FgFr92oEdj426u Yjlk5WCZ+cALYjYQTaQuoWup/OZzNhIXLeBPFdxsc7y+UN7uONnUHVrw77Gy7MDFlr swqxjHp7PqGrZN3bNFIRkPl8CcdoN6tBDU8eGBn7GT/4Z/DNXZ183Q5yDwkbQ3xBu5 rlvkbZrJ4PMTQ== Received: by macsyma.thunk.org (Postfix, from userid 15806) id CDC3EF6845D; Mon, 17 Aug 2026 23:04:43 -0400 (EDT) Date: Mon, 17 Aug 2026 23:04:43 -0400 From: "Theodore Tso" To: Jan Kara Cc: Guanghui Yang <3497809730@qq.com>, Andreas Dilger , Baokun Li , Ojaswin Mujoo , Ritesh Harjani , Zhang Yi , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] ext4: orphan tracking after a failed truncate Message-ID: References: <66vcv4ircw5mqadt4eki52hujmykrrsqp2cux4qvn37v6kzvs7@d7ys45emz3dr> Precedence: bulk X-Mailing-List: linux-kernel@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: <66vcv4ircw5mqadt4eki52hujmykrrsqp2cux4qvn37v6kzvs7@d7ys45emz3dr> On Mon, Aug 17, 2026 at 05:56:24PM -0500, Jan Kara wrote: > This is expected. If you hit IO error on metadata, all bets are off wrt > filesystem consistency. Running e2fsck to fix the filesystem is the only > way to establish filesystem consistency again. So there's nothing to fix in > the kernel really as the fact that an inode with blocks beyond EOF is not > on orphan list is just a little nuissance... If we want to let the system administrator know that they should run fsck, then perhaps we should call ext4_error_inode() and return EFSCORRUPTED instead of EIO. In general, if we are in the middle of modifying file system metadata, and we run into an error, we should either try to back out the change so the file system is consistent. HOWEVER, in this case, blocks beyond EOF is not really a file system consistency issue, since you can get blocks beyond EOF by using the fallocate system call with FALLOC_FL_KEEP_SIZE flag. > Quick note for Ted: these kind of reports where LLM complains about > inconsistencies after IO errors or other catastrophic failures are rather > frequent. I think that would be a good candidate for an ext4 specific > prompt for LLMs to explain to it that after metadata IO failure filesystem > inconsistencies are expected and we should just strive to limit lost data. Unfortunately, it's a bit tricky to do that. The problem is that LLM's aren't consistent about how they handle AGENTS.md or CLAUDE.md file. Despite AGENTS.md being a standard promulgated by the LF's Agentic AI Foundation, not all LLM harneses will read a AGENTS.md file located a directory outside of the repository root directory. So if we put LLM Harness directives in fs/ext4/AGENTS.md, some harnesses (including Github's Copilot or OpenAI Codex) won't read it unless there is an explicit request read it in the top-level AGENTS.md file. We could have the top-level AGENTS.md say that for any file-system related code, please read fs/AGENTS.md, and then the fs/AGENTS.md file could say that in case of a btrfs-related issue, read fs/btrfs/AGENTS.md, and if it's an ext4-related, to please read fs/ext4/AGENTS.md, etc. It very quickly becomes a mess. Worse, Claude has steadfastly refused to honor the AGENTS.md file (although at least it will read CLAUDE.md file in subdirectories). So we'd have to have CLAUDE.md file be a symlink to AGENTS.md, or to have an instruction in CLAUDE.md to read AGENTS.md. Probably the best we can do is to put generic documentation in Documentation/filesystems/ext4, meant for both humans and LLM's, describing ext4's error handling philosophy, and hope the LLM harnesses bothers to read it. - Ted