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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3391C4332F for ; Fri, 30 Dec 2022 22:25:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235581AbiL3WZn (ORCPT ); Fri, 30 Dec 2022 17:25:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235435AbiL3WZl (ORCPT ); Fri, 30 Dec 2022 17:25:41 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 281A31D0CF for ; Fri, 30 Dec 2022 14:25:41 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B8BE061C17 for ; Fri, 30 Dec 2022 22:25:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E6B0C433D2; Fri, 30 Dec 2022 22:25:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672439140; bh=f6xUFqe0tuL0gkFsXMaYpLY5bIZijg1sUNlCENNdntc=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=WuNSLTTVYOyTLigxfzvtzDm8ORrWHSL/N0AkDFtHGkZ+pMq2XDCadnjrSF7y8cAHN +t1c3rOsrfRAvQ2044y7rDKto+NQRO66Nmr8P4Dp1+u489fQrtZRo/klH5HZiQyFHu b27a/d7oQWvmFOwibXbbp2YDwJiVkxXiSTim4CP9XDRtEmWUk/eMx0H8kUVHeDNkGE i1v5VRzTxntgHjwimEdnwlfy84aw4pmrb1H30RnfFIIS4j3rcwPUyLgTJYX7dsb98Y hHLmqm4TB+rqCPwssqry8wFin0YKneims33pBf0Ki/TV/ggFWnJVkXjVI7+EL6AdVK bE9V5bqg01xGg== Subject: [PATCHSET v24.0 0/2] xfs: fix rmap btree key flag handling From: "Darrick J. Wong" To: djwong@kernel.org Cc: linux-xfs@vger.kernel.org Date: Fri, 30 Dec 2022 14:11:18 -0800 Message-ID: <167243827872.684208.12327644447561431612.stgit@magnolia> In-Reply-To: References: User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Hi all, This series fixes numerous flag handling bugs in the rmapbt key code. The most serious transgression is that key comparisons completely strip out all flag bits from rm_offset, including the ones that participate in record lookups. The second problem is that for years we've been letting the unwritten flag (which is an attribute of a specific record and not part of the record key) escape from leaf records into key records. The solution to the second problem is to filter attribute flags when creating keys from records, and the solution to the first problem is to preserve *only* the flags used for key lookups. The ATTR and BMBT flags are a part of the lookup key, and the UNWRITTEN flag is a record attribute. This has worked for years without generating user complaints because ATTR and BMBT extents cannot be shared, so key comparisons succeed solely on rm_startblock. Only file data fork extents can be shared, and those records never set any of the three flag bits, so comparisons that dig into rm_owner and rm_offset work just fine. A filesystem written with an unpatched kernel and mounted on a patched kernel will work correctly because the ATTR/BMBT flags have been conveyed into keys correctly all along, and we still ignore the UNWRITTEN flag in any key record. This was what doomed my previous attempt to correct this problem in 2019. A filesystem written with a patched kernel and mounted on an unpatched kernel will also work correctly because unpatched kernels ignore all flags. With this patchset applied, the scrub code gains the ability to detect rmap btrees with incorrectly set attr and bmbt flags in the key records. After three years of testing, I haven't encountered any problems. If you're going to start using this mess, you probably ought to just pull from my git trees, which are linked below. This is an extraordinary way to destroy everything. Enjoy! Comments and questions are, as always, welcome. --D kernel git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=rmap-btree-fix-key-handling xfsprogs git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=rmap-btree-fix-key-handling --- fs/xfs/libxfs/xfs_rmap_btree.c | 40 +++++++++++++++++++++++------- fs/xfs/scrub/btree.c | 10 ++++++++ fs/xfs/scrub/btree.h | 2 ++ fs/xfs/scrub/rmap.c | 53 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 95 insertions(+), 10 deletions(-)