From mboxrd@z Thu Jan 1 00:00:00 1970 From: Trond Myklebust Subject: Re: 2.6.38-rc2... NFS sillyrename is broken... Date: Wed, 26 Jan 2011 15:14:27 -0500 Message-ID: <1296072867.7127.26.camel@heimdal.trondhjem.org> References: <1295998215.6867.22.camel@heimdal.trondhjem.org> <21515.1296030022@jrobl> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Cc: linux-nfs@vger.kernel.org, Nick Piggin , Linux Filesystem Development To: "J. R. Okajima" Return-path: Received: from mx2.netapp.com ([216.240.18.37]:16798 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751736Ab1AZUOx convert rfc822-to-8bit (ORCPT ); Wed, 26 Jan 2011 15:14:53 -0500 In-Reply-To: <21515.1296030022@jrobl> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, 2011-01-26 at 17:20 +0900, J. R. Okajima wrote: > (CC-ed Nick Piggin) > > Trond Myklebust: > > Something in the recent VFS churn appears to have broken NFS > > sillyrename. > > > > Currently, when I try to unlink() a file that is being held open by > > another process, I do indeed see that file getting renamed to > > a .nfsxxxxxxx file, but when the file is closed, the .nfsxxxxx file > > sticks around until I unlink() it again. > > > > I'll have a look tomorrow at what is going wrong, but I figured I'd ask > > on the list in case someone has a suspect... > > I noticed this issue yesterday and found the change for removing > dcache_lock is suspicious. > By the commit 949854d > 2011-01-07 fs: Use rename lock and RCU for multi-step operations > dentry->d_parent = NULL; > is added into the beginning of VFS d_kill(). > > Later d_kill() calls dentry_iput(), d_op->d_iput() which is > nfs_dentry_iput() in NFS. > Then nfs_dentry_iput() calls nfs_complete_unlink(), nfs_call_unlink(). > Here nfs_call_unlink() calls dget_parent() and when the result is NULL, > it skips the actual unlink. Finally the "silly-renamed" dentry > remains. Agreed. That looks like it explains the breakage. > Can we stop "dentry->d_parent = NULL" > when (d->flags & DCACHE_NFSFS_RENAMED) is true? Nick? The alternative would be to add a callback that can be called after dentry_iput() if DCACHE_NFSFS_RENAMED is true, and that takes the parent and (negative) dentry as the arguments. sillyrename doesn't need the inode as an argument, but it definitely needs the parent dentry so that it can check for races with ->lookup()... -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com