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 9E09BC3DA6F for ; Thu, 24 Aug 2023 16:13:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242277AbjHXQMx (ORCPT ); Thu, 24 Aug 2023 12:12:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242442AbjHXQMw (ORCPT ); Thu, 24 Aug 2023 12:12:52 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8958919A5; Thu, 24 Aug 2023 09:12:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1A78E64542; Thu, 24 Aug 2023 16:12:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E65BC433C8; Thu, 24 Aug 2023 16:12:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692893569; bh=O4XTL4rB4zuJHdhNExBFZy/du5pB054CERvuMKtJo04=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Zd172NVLZC5LbrmylYiXnh7Z4wYQFOSuJ7DDolfUA3DHLZG6W+sqb89yxtAaMibyP CPrfKx29DslsV3KU+HncJRlvwUTzBZfkesWbzwQzKST6pAlPlkck5+80JLq60V0zku JMjFUyHvbjFQreQLB0ie88gbJmApjOxgISZZqEQwX2JpFsyTTTz7HtzjFXX52muSs2 ieXZjrwZ0wq52Q3eXu/NIexjplxgEH6qXSAMMUct6nmJE9jnDFtZ1rE6km73vFH5SI n464ftVY7dDile8dPkSyHM6q6oLsPc9CzfPN833JM0xZPMxHCG7yEaAZMmuNTqTrhW GhECdY5okFEvA== Date: Thu, 24 Aug 2023 09:12:48 -0700 From: "Darrick J. Wong" To: cheng.lin130@zte.com.cn Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, jiang.yong5@zte.com.cn, wang.liang82@zte.com.cn, liu.dong3@zte.com.cn Subject: Re: [PATCH] xfs: introduce protection for drop nlink Message-ID: <20230824161248.GM11263@frogsfrogsfrogs> References: <202308241543526473806@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202308241543526473806@zte.com.cn> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Aug 24, 2023 at 03:43:52PM +0800, cheng.lin130@zte.com.cn wrote: > From: Cheng Lin > An dir nlinks overflow which down form 0 to 0xffffffff, cause the > directory to become unusable until the next xfs_repair run. > > Introduce protection for drop nlink to reduce the impact of this. > And produce a warning for directory nlink error during remove. > > Signed-off-by: Cheng Lin > --- > fs/xfs/xfs_inode.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index 9e62cc5..536dbe4 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -919,6 +919,15 @@ STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag, > xfs_trans_t *tp, > xfs_inode_t *ip) > { > + xfs_mount_t *mp; > + > + if (VFS_I(ip)->i_nlink == 0) { > + mp = ip->i_mount; > + xfs_warn(mp, "%s: Deleting inode %llu with no links.", > + __func__, ip->i_ino); > + return 0; > + } > + > xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG); > > drop_nlink(VFS_I(ip)); I'm not sure how nlink would ever get to 0xFFFFFFFF since the VFS won't let a link count exceed s_max_links, and XFS sets that to 0x7FFFFFFF. Unless, of course, you did that outside of Linux. That said, why wouldn't you /pin/ the link count at -1U instead of allowing it to overflow to zero? Could you please take a look at this patch that's waiting in my submission queue? https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git/commit/?h=inode-repair-improvements&id=05f5a82efa6395c92038e18e008aaf7154238f27 --D > @@ -2442,7 +2451,12 @@ STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag, > */ > if (is_dir) { > ASSERT(VFS_I(ip)->i_nlink >= 2); > - if (VFS_I(ip)->i_nlink != 2) { > + if (VFS_I(ip)->i_nlink < 2) { > + xfs_warn(ip->i_mount, > + "%s: Remove dir (inode %llu) with invalid links.", > + __func__, ip->i_ino); > + } > + if (VFS_I(ip)->i_nlink > 2) { > error = -ENOTEMPTY; > goto out_trans_cancel; > } > -- > 1.8.3.1