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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 E54C8C4332E for ; Mon, 23 Mar 2020 19:09:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B77D72051A for ; Mon, 23 Mar 2020 19:09:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NZUCg5wj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727624AbgCWTJB (ORCPT ); Mon, 23 Mar 2020 15:09:01 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:32949 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727600AbgCWTJB (ORCPT ); Mon, 23 Mar 2020 15:09:01 -0400 Received: by mail-wm1-f65.google.com with SMTP id r7so767605wmg.0 for ; Mon, 23 Mar 2020 12:09:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=8Tgigb4uCARLyAFc90cRmjh9Wu2sjVgvF4ampomjYAU=; b=NZUCg5wj8ViHEH0D5w6er0wCFDKtXWF85zFY1/FZvF0xyjxTr16dX4H1GqsbqAde47 AmGNsJ6GhvSZZyntmwmrzERszcN5vshQwaC8cQMQBTWvm1SUpX9SdPZPvC86X1teSw4A yQTXD0R8Z78hCAHoL95eR6NSQvsxZSs1v2aycymcVGG3WpftyGMbjlwO+mCVbqy6EjCh ATckIObmf4bMkIMPyxpEccZLancLRPXUcKxQAYH5xmB5mVMBhT1B9ghKONi80s9tX+J2 RfQ2TjZLuRMhwHnO2+tBrNP5Q33GPDla6VSJKS5RCMBgk/zV7PFmkzu7ehatHHesThA0 Zcmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=8Tgigb4uCARLyAFc90cRmjh9Wu2sjVgvF4ampomjYAU=; b=YcLaiudoT90l8Xi49R701CZT65SwN4lNxnuTonwXk05xI81DZZXhF00KeHCvX6D4zU IHRpNK+NaMpuqEYTsbEqUhpImNMg0+CI4/jrqzRoYCrdn+GsVNhUJYkpPmfp9ehfQGwH cjNarxu0cBv3S5YE/YTPXtav8oSbX28DJxYJws04+FUnbVvMrHwPmooKXdWud1emTL0b cUybpGnXXHXpx5aZoNYzeWrcA0DGv9zjCMbCWQh8ruAyh8JPTV07SizdvdZUVV2RmZTA xGgaY9a+W4VjcSeX7AOmYqqYb31Sx4OGT5WaORjfNqVCRD4C5dQvyxgStYF29q5j8m8+ eYdg== X-Gm-Message-State: ANhLgQ3XuiVDsS41zRFV8B98zxw/hS2OgSDb3s4nlTw+/nS8V3cTIA3z NGayn542SmM4eZ1Jhk96rZ2jIp1z X-Google-Smtp-Source: ADFU+vt6LwzdLTMl8Vg+nCbfwvySW169xwVPG/HuYSQVlZ7T+HfzNVkMBd7RECuopiWJ8D2gL7nN+g== X-Received: by 2002:a05:600c:581:: with SMTP id o1mr889436wmd.111.1584990539283; Mon, 23 Mar 2020 12:08:59 -0700 (PDT) Received: from localhost.localdomain ([141.226.9.174]) by smtp.gmail.com with ESMTPSA id f14sm740275wmb.3.2020.03.23.12.08.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Mar 2020 12:08:58 -0700 (PDT) From: Amir Goldstein To: Miklos Szeredi Cc: linux-unionfs@vger.kernel.org Subject: [PATCH] ovl: fix WARN_ON nlink drop to zero Date: Mon, 23 Mar 2020 21:08:50 +0200 Message-Id: <20200323190850.3091-1-amir73il@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-unionfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org Changes to underlying layers should not cause WARN_ON(), but this repro does: mkdir w l u mnt sudo mount -t overlay -o workdir=w,lowerdir=l,upperdir=u overlay mnt touch mnt/h ln u/h u/k rm -rf mnt/k rm -rf mnt/h dmesg ------------[ cut here ]------------ WARNING: CPU: 1 PID: 116244 at fs/inode.c:302 drop_nlink+0x28/0x40 After upper hardlinks were added while overlay is mounted, unlinking all overlay hardlinks drops overlay nlink to zero before all upper inodes are unlinked. Detect too low i_nlink before unlink/rename and set the overlay nlink to the upper inode nlink (minus one for an index entry). Reported-by: Phasip Signed-off-by: Amir Goldstein --- fs/overlayfs/util.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) Miklos, This fix passed the reported reproducers (with index=off), overlay/034 with (index=on) and overlay/034 with s/LOWER/UPPER: -lowerdir=$OVL_BASE_SCRATCH_MNT/$OVL_LOWER +lowerdir=$OVL_BASE_SCRATCH_MNT/$OVL_UPPER workdir=$OVL_BASE_SCRATCH_MNT/$OVL_WORK As well as the rest of overlay/quick group. I will post the overlay/034 fork as a separate test later. Thanks, Amir. diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 36b60788ee47..e894a14857c7 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -734,7 +734,9 @@ static void ovl_cleanup_index(struct dentry *dentry) int ovl_nlink_start(struct dentry *dentry) { struct inode *inode = d_inode(dentry); + struct inode *iupper = ovl_inode_upper(inode); const struct cred *old_cred; + int index_nlink; int err; if (WARN_ON(!inode)) @@ -764,7 +766,26 @@ int ovl_nlink_start(struct dentry *dentry) if (err) return err; - if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode)) + if (d_is_dir(dentry)) + goto out; + + /* index adds +1 to upper nlink */ + index_nlink = !!ovl_test_flag(OVL_INDEX, inode); + if (iupper && (iupper->i_nlink - index_nlink) > inode->i_nlink) { + pr_warn_ratelimited("inode nlink too low (%pd2, ino=%lu, nlink=%u, upper_nlink=%u)\n", + dentry, inode->i_ino, inode->i_nlink, + iupper->i_nlink - index_nlink); + /* + * Upper hardlinks were added while overlay is mounted. + * Unlinking all overlay hardlinks would drop overlay nlink to + * zero before all upper inodes are unlinked. As a safety + * measure, when that situation is detected, set the overlay + * nlink to the upper inode nlink minus one for the index entry. + */ + set_nlink(d_inode(dentry), iupper->i_nlink - index_nlink); + } + + if (!index_nlink) goto out; old_cred = ovl_override_creds(dentry->d_sb); -- 2.17.1