linux-kernel - Re: nfsv2 ref leak in 2.6.24?

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Date:	Sat, 20 Oct 2007 17:35:19 -0400
From:	Erez Zadok <ezk@...sunysb.edu>
To:	Trond Myklebust <trond.myklebust@....uio.no>, bfields@...ldses.org,
	nfs@...ts.sourceforge.net, neilb@...e.de,
	linux-kernel@...r.kernel.org, ezk@...sunysb.edu
Subject: Re: nfsv2 ref leak in 2.6.24? 

In message <200710201904.l9KJ4d4Z019993@...ra.fsl.cs.sunysb.edu>, Erez Zadok writes:
> In message <1192900351.7440.6.camel@...mdal.trondhjem.org>, Trond Myklebust writes:
[...]
> > Looking at
> > nfs_proc_create(), there is indeed a missing call to
> > nfs_mark_for_revalidate(). The reason why you need such a call being the
> > usual one: NFSv2 doesn't provide post-op attributes for the directory.
> > 
> > The patch below ought to fix the problem.
> 
> It fixes some, but breaks others.  The test script I sent yesterday indeed
> passes.  And more of my unionfs-on-nfs2 tests pass, but not all.  Three of
> my unionfs tests (create w/ copyup, unlink open files, and unlink with a
> whiteout) fail b/c they detect leftover silly-renamed files.  Worse, now the
> same three tests also fail when I use unionfs on top of nfs3/nfs4: before
> the one line fix below, unionfs-on-nfsv3/4 worked fine.
> 
> Was there any significant semantic change in the behaviour of silly-renamed
> files in nfs in 2.6.24?  If so, then I may have to change how unionfs
> handles refcounts and such.
> 
> I'll try to dig deeper and see if I can come up with a small test case that
> doesn't involve unionfs.
> 
> Thanks,
> Erez.
> 
> > Cheers
> >   Trond
> > ---------------------- CUT HERE -----------------------
> > From: Trond Myklebust <Trond.Myklebust@...app.com>
> > Date: Sat, 20 Oct 2007 13:07:21 -0400
> > NFSv2: Ensure that the directory metadata gets revalidated on file create
> > 
> > Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
> > ---
> > 
> >  fs/nfs/proc.c |    1 +
> >  1 files changed, 1 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
> > index 97669ed..4f80d88 100644
> > --- a/fs/nfs/proc.c
> > +++ b/fs/nfs/proc.c
> > @@ -211,6 +211,7 @@ nfs_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
> >  	nfs_fattr_init(&fattr);
> >  	dprintk("NFS call  create %s\n", dentry->d_name.name);
> >  	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
> > +	nfs_mark_for_revalidate(dir);
> >  	if (status == 0)
> >  		status = nfs_instantiate(dentry, &fhandle, &fattr);
> >  	dprintk("NFS reply create: %d\n", status);
> 
> Erez.

Trond, I verified that w/ the above patch the problem is w/ nfs: the client
leaves .nfsXXX files behind for every file unlinked while open.  Let me know
when you get a fix and I'll test it.

Cheers,
Erez.
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