From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [patch for 2.6.27? 1/2] nfs: BUG_ON in nfs_follow_mountpoint Date: Mon, 22 Sep 2008 14:10:53 -0700 Message-ID: <200809222110.m8MLAsCo029914@imap1.linux-foundation.org> Cc: bfields@fieldses.org, linux-nfs@vger.kernel.org, akpm@linux-foundation.org, den@openvz.org, Trond.Myklebust@netapp.com To: trond.myklebust@fys.uio.no Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:50176 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753154AbYIVVLm (ORCPT ); Mon, 22 Sep 2008 17:11:42 -0400 Sender: linux-nfs-owner@vger.kernel.org List-ID: From: "Denis V. Lunev" Unfortunately, BUG_ON(IS_ROOT(dentry)) can happen inside nfs_follow_mountpoint with NFS running Fedora 8 using a specific setup. See https://bugzilla.redhat.com/show_bug.cgi?id=458622 So the situation should be handled on NFS client gracefully. (Trond: I'm not convinced that ESTALE is the correct error to return to the user. ESTALE has a very precise meaning in the NFS protocol: it tells you that access to the object has been revoked. That again means either that either the object has been deleted, or it is no longer exported by the server to this client. In the case referred to by Denis, the source of the bug is a broken server, and so I'd expect that EIO is probably more appropriate.) Signed-off-by: Denis V. Lunev Cc: Trond Myklebust Cc: J. Bruce Fields Signed-off-by: Andrew Morton --- fs/nfs/namespace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff -puN fs/nfs/namespace.c~nfs-bug_on-in-nfs_follow_mountpoint fs/nfs/namespace.c --- a/fs/nfs/namespace.c~nfs-bug_on-in-nfs_follow_mountpoint +++ a/fs/nfs/namespace.c @@ -105,7 +105,10 @@ static void * nfs_follow_mountpoint(stru dprintk("--> nfs_follow_mountpoint()\n"); - BUG_ON(IS_ROOT(dentry)); + err = -ESTALE; + if (IS_ROOT(dentry)) + goto out_err; + dprintk("%s: enter\n", __func__); dput(nd->path.dentry); nd->path.dentry = dget(dentry); _