From patchwork Tue Aug 27 13:22:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 11116941 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 99A10112C for ; Tue, 27 Aug 2019 13:22:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81ADE206BF for ; Tue, 27 Aug 2019 13:22:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729951AbfH0NWU (ORCPT ); Tue, 27 Aug 2019 09:22:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:48270 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729159AbfH0NWU (ORCPT ); Tue, 27 Aug 2019 09:22:20 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 85379B066; Tue, 27 Aug 2019 13:22:19 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: Anand Jain Subject: [PATCH] btrfs: tree-checker: Fix wrong check on max devid Date: Tue, 27 Aug 2019 21:22:06 +0800 Message-Id: <20190827132206.1483-1-wqu@suse.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Btrfs doesn't reuse devid, thus if we add and delete device in a loop, we can increase devid to higher value, triggering tree checker to give a false alert. But we still don't want to give up the devid check, so here we compromise by setting a larger devid upper limit, 1<<32. So crazy scripts can't bump devid to that high value easily, while we can still detect obviously wrong devid. Reported-by: Anand Jain Fixes: ab4ba2e13346 ("btrfs: tree-checker: Verify dev item") Signed-off-by: Qu Wenruo --- fs/btrfs/tree-checker.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 43e488f5d063..f9d24f01801e 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -686,9 +686,14 @@ static void dev_item_err(const struct extent_buffer *eb, int slot, static int check_dev_item(struct extent_buffer *leaf, struct btrfs_key *key, int slot) { - struct btrfs_fs_info *fs_info = leaf->fs_info; struct btrfs_dev_item *ditem; - u64 max_devid = max(BTRFS_MAX_DEVS(fs_info), BTRFS_MAX_DEVS_SYS_CHUNK); + /* + * Btrfs doesn't really reuse devid, thus devid can increase to any + * value, but we don't believe a devid higher than (1<<32) is really + * valid. This could at least detect bitflip at the higher + * 32 bits while still consider high devid valid. + */ + u64 max_devid = (1ULL << 32); if (key->objectid != BTRFS_DEV_ITEMS_OBJECTID) { dev_item_err(leaf, slot,