From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C2ABC4320A for ; Tue, 17 Aug 2021 20:27:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07F6761053 for ; Tue, 17 Aug 2021 20:27:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234546AbhHQU1f (ORCPT ); Tue, 17 Aug 2021 16:27:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:59634 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230515AbhHQU1f (ORCPT ); Tue, 17 Aug 2021 16:27:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A15986023E; Tue, 17 Aug 2021 20:27:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629232021; bh=7uXwMUE6nCVLGwC/jf/GBBmqfuoSPzQ5my11HXxJJ+8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XDVt4BIw8TZ4dDwPOYDNZ/G2MStCyFFOrVF8PKDzwzYf5nzchnVIan7DsQQFZTMyw /pKEAn4QeBsUxi5xf1lm/n79gqavsC2qCXa+XlN4DvCCjFFS072Wh1VBjL0U78Gy19 frL/rs06eFjKxkzUQlv+77vJv/VAH1GfNu8Or52MXcLl51OQkoMKdVAdhb73d+b/R/ L/ZbqvAzPueK/JiwfyPkooo4BcGXkRwCS8BEWlYbSlQq9/z72QkJOeprhsne5ZekPo uLpARkcYqMiThu886GNZg5/bKH0rvHUg2aYI1ja2foEfELKrOhlJMwkbWTpiCEej2O Hrtd2cL8QOdig== Date: Tue, 17 Aug 2021 13:27:00 -0700 From: Eric Biggers To: Jaegeuk Kim Cc: Christoph Hellwig , Chao Yu , Theodore Ts'o , linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] f2fs: remove broken support for allocating DIO writes Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Aug 17, 2021 at 11:57:46AM -0700, Jaegeuk Kim wrote: > On 08/17, Christoph Hellwig wrote: > > On Mon, Aug 16, 2021 at 07:03:21PM -0700, Eric Biggers wrote: > > > Freeing preallocated blocks on error would be better than nothing, although note > > > that the preallocated blocks may have filled an arbitrary sequence of holes -- > > > so simply truncating past EOF would *not* be sufficient. > > > > > > But really filesystems need to be designed to never expose uninitialized data, > > > even if I/O errors or a sudden power failure occurs. It is unfortunate that > > > f2fs apparently wasn't designed with that goal in mind. > > > > > > In any case, I don't think we can proceed with any other f2fs direct I/O > > > improvements until this data leakage bug can be solved one way or another. If > > > my patch to remove support for allocating writes isn't acceptable and the > > > desired solution is going to require some more invasive f2fs surgery, are you or > > > Chao going to work on it? I'm not sure there's much I can do here. > > > > Btw, this is generally a problem for buffered I/O as well, although the > > window for exposing uninitialized blocks on a crash tends to be smaller. > > How about adding a warning message when we meet an error with preallocated > unwritten blocks? In the meantime, can we get the Eric's patches for iomap > support? I feel that we only need to modify the preallocation and error > handling parts? A warning message would do nothing to prevent uninitialized blocks from being leaked to userspace. - Eric