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 8EEC4944F; Wed, 6 Aug 2025 14:51:34 +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=1754491903; cv=none; b=uzSd4gMQGidYxI22kcbP5yXWKqo4bRvs/JftEKUzPP02rv/9IiAqmdoKp3JxmDoHNt6fmrKsV0bmOo7JiHlWYBG+Mt4h+M4NWYByIG5yhrDoxbCiM/vxMPChrgyk8RF/Rp3RFaQLe9fF119+uYjln62vx87EQYWLaKQ1/u6CFho= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754491903; c=relaxed/simple; bh=uvBDByLweRe4L0+0bNxfGe3e9GlYbMP9yIrYw/RwM24=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oZeyW6W5kXIRiswQjUxUluuX7cyp8VdrdVV/V5OJzJVFOHcfLJ3ni7PdioE4dWL4g8imdH+g4YnlhUJAIy8QUm+ZVnrpUyzOUJRHcGlStl6oFAMJuzQBmFMA4LgT4mfwMt6f2Wp20bCBTi+0XX9dLVWMiaMoFNeJwZbvZ84V3GE= 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=Keyo+QW4; 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="Keyo+QW4" 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=S3wdBIOLGEb/dP4L+k9B4Zn54dlvDvbbF5Vrp6IEWAE=; b=Keyo+QW4qD4sSKo5MwOJ7rpWON AzJ8xbNru1fyVHVJV2lDT/G3tmHeYXHQzk63MQDCl8JO/TkJVTarNd5KHWeDuQGez9IAsTQj6AdkA mEg88q7La1upTIhV+/PHr7WqceDh6/fxq57CdNZKlIZdUHX3PAoDHL74NqCtpxUeeDI/pfKM8YDBz jVk3cFqde6eNnnVRCZS519HiUTynHZBfgrneKVlba9R7jsF1+HMRP44a1wjsBRofqx6WCo5PfMaU+ J+0Q8P9OP4Tf19hJvpr/hr0xv0YY89Yc++Cie1o4KuVwOYnHCImZ7hNaf+iSX+aKGCqGYPEEPbJZZ bQiRZMsA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1ujfUM-0000000FUPY-0hUG; Wed, 06 Aug 2025 14:51:34 +0000 Date: Wed, 6 Aug 2025 07:51:34 -0700 From: Christoph Hellwig To: Keith Busch Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, snitzer@kernel.org, axboe@kernel.dk, dw@davidwei.uk, brauner@kernel.org, Keith Busch Subject: Re: [PATCHv2 0/7] direct-io: even more flexible io vectors Message-ID: References: <20250805141123.332298-1-kbusch@meta.com> Precedence: bulk X-Mailing-List: linux-block@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: <20250805141123.332298-1-kbusch@meta.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Just jumping in while travelling with almost time available: I like the idea, but you have to be really, really careful for writes through file systems with this. Deferred errors happening after bio submission are nasty and we tend to get things wrong there too often. So this needs to come with an xfstests to actually hit the alignment errors, including something that is not the first bio submitted. Even with that it will change behavior quite a bit, e.g. for file systems that can do direct I/O write without the exclusive i_rwsem will leak newly allocated space on errors asynchronously reported through bio completions, so you'll need to get fs maintainer buy in for that. Given all that I'm not sure converting the legacy fs/direct-io.c path is such a good idea as the only file systems left using it are those that are more less unmaintained (or at least severely undermaintained).